Sample records for vein blood flow

  1. An Artificial Cadaveric Leg Blood Flow System for Endoscopic Vein Harvesting Simulation. (United States)

    Karras, Constantine L; DeDonato, Emily A; DiBartola, Kaitlin K; Zhao, Jin-Cheng

    Despite being the most common training model for endoscopic vein harvesting, cadaveric legs are limited by their absence of blood flow, resulting in a faded vascular appearance. Because the saphenous vein and the surrounding tissue seem less distinguishable, dissection of the saphenous vein and bipolar coagulation of its branches becomes increasingly inefficient and difficult. An inexpensive artificial blood flow system was developed to overcome this limitation. A cadaveric leg was thawed to a soft and yielding degree, and the saphenous vein was dissected medial and proximal to the medial malleolus. An artificial blood solution was prepared by dissolving 4% protein powder, red dye, and a contrast agent-for x-ray visualization-in saline. The solution was perfused through the saphenous vein and artery. The open ends of the vessels were temporarily clamped after the perfusion had been completed. Blood flow within the vessels was confirmed via angiography and endoscopic visualization of the leg's vessels. A bleeding effect was observed when the saphenous vein was perforated or when a vascular branch was transected. Conversely, a tight seal indicated successful bipolar coagulation of a branch, providing an objective, quantifiable assessment parameter. The artificial blood flow system helps overcome the limitations of the cadaveric leg, creating a more realistic and inexpensive model for endoscopic vein harvesting simulation training.

  2. In vivo analysis of physiological 3D blood flow of cerebral veins. (United States)

    Schuchardt, Florian; Schroeder, Laure; Anastasopoulos, Constantin; Markl, Michael; Bäuerle, Jochen; Hennemuth, Anja; Drexl, Johann; Valdueza, José M; Mader, Irina; Harloff, Andreas


    To visualize and quantify physiological blood flow of intracranial veins in vivo using time-resolved, 3D phase-contrast MRI (4D flow MRI), and to test measurement accuracy. Fifteen healthy volunteers underwent repeated ECG-triggered 4D flow MRI (3 Tesla, 32-channel head coil). Intracranial venous blood flow was analysed using dedicated software allowing for blood flow visualization and quantification in analysis planes at the superior sagittal, straight, and transverse sinuses. MRI was evaluated for intra- and inter-observer agreement and scan-rescan reproducibility. Measurements of the transverse sinuses were compared with transcranial two-dimensional duplex ultrasound. Visualization of 3D blood flow within cerebral sinuses was feasible in 100 % and within at least one deep cerebral vein in 87 % of the volunteers. Blood flow velocity/volume increased along the superior sagittal sinus and was lower in the left compared to the right transverse sinus. Intra- and inter-observer reliability and reproducibility of blood flow velocity (mean difference 0.01/0.02/0.02 m/s) and volume (mean difference 0.0002/-0.0003/0.00003 l/s) were good to excellent. High/low velocities were more pronounced (8 % overestimation/9 % underestimation) in MRI compared to ultrasound. Four-dimensional flow MRI reliably visualizes and quantifies three-dimensional cerebral venous blood flow in vivo and is promising for studies in patients with sinus thrombosis and related diseases. • 4D flow MRI can be used to visualize and quantify physiological cerebral venous haemodynamics • Flow quantification within cerebral sinuses reveals high reliability and accuracy of 4D flow MRI • Blood flow volume and velocity increase along the superior sagittal sinus • Limited spatial resolution currently precludes flow quantification in small cerebral veins.

  3. In vivo analysis of physiological 3D blood flow of cerebral veins

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    Schuchardt, Florian; Schroeder, Laure; Baeuerle, Jochen; Harloff, Andreas [University Medical Centre, Department of Neurology, Freiburg (Germany); Anastasopoulos, Constantin [University Medical Center, Department of Neuropaediatrics and Muscle Disorders, Freiburg (Germany); University Medical Centre, Department of Neuroradiology, Freiburg (Germany); Markl, Michael [Northwestern University, Department of Radiology, Feinberg School of Medicine and McCormick School of Engineering, Chicago, IL (United States); Hennemuth, Anja; Drexl, Johann [Fraunhofer MEVIS, Bremen (Germany); Valdueza, Jose M. [Neurological Center, Segeberger Kliniken, Bad Segeberg (Germany); Mader, Irina [University Medical Centre, Department of Neuroradiology, Freiburg (Germany)


    To visualize and quantify physiological blood flow of intracranial veins in vivo using time-resolved, 3D phase-contrast MRI (4D flow MRI), and to test measurement accuracy. Fifteen healthy volunteers underwent repeated ECG-triggered 4D flow MRI (3 Tesla, 32-channel head coil). Intracranial venous blood flow was analysed using dedicated software allowing for blood flow visualization and quantification in analysis planes at the superior sagittal, straight, and transverse sinuses. MRI was evaluated for intra- and inter-observer agreement and scan-rescan reproducibility. Measurements of the transverse sinuses were compared with transcranial two-dimensional duplex ultrasound. Visualization of 3D blood flow within cerebral sinuses was feasible in 100 % and within at least one deep cerebral vein in 87 % of the volunteers. Blood flow velocity/volume increased along the superior sagittal sinus and was lower in the left compared to the right transverse sinus. Intra- and inter-observer reliability and reproducibility of blood flow velocity (mean difference 0.01/0.02/0.02 m/s) and volume (mean difference 0.0002/-0.0003/0.00003 l/s) were good to excellent. High/low velocities were more pronounced (8 % overestimation/9 % underestimation) in MRI compared to ultrasound. Four-dimensional flow MRI reliably visualizes and quantifies three-dimensional cerebral venous blood flow in vivo and is promising for studies in patients with sinus thrombosis and related diseases. (orig.)

  4. Imaging of the Finger Vein and Blood Flow for Anti-Spoofing Authentication Using a Laser and a MEMS Scanner. (United States)

    Lee, Jaekwon; Moon, Seunghwan; Lim, Juhun; Gwak, Min-Joo; Kim, Jae Gwan; Chung, Euiheon; Lee, Jong-Hyun


    A new authentication method employing a laser and a scanner is proposed to improve image contrast of the finger vein and to extract blood flow pattern for liveness detection. A micromirror reflects a laser beam and performs a uniform raster scan. Transmissive vein images were obtained, and compared with those of an LED. Blood flow patterns were also obtained based on speckle images in perfusion and occlusion. Curvature ratios of the finger vein and blood flow intensities were found to be nearly constant, regardless of the vein size, which validated the high repeatability of this scheme for identity authentication with anti-spoofing.

  5. Blood flow velocity in the Popliteal Vein using Transverse Oscillation Ultrasound

    DEFF Research Database (Denmark)

    Bechsgaard, Thor; Lindskov Hansen, Kristoffer; Brandt, Andreas Hjelm


    Chronic venous disease is a common condition leading to varicose veins, leg edema, post-thrombotic syndrome and venous ulcerations. Ultrasound (US) is the main modality for examination of venous disease. Color Doppler and occasionally spectral Doppler US (SDUS) are used for evaluation of the venous...... flow. Peak velocities measured by SDUS are rarely used in a clinical setting for evaluating chronic venous disease due to inadequate reproducibility mainly caused by the angle dependency of the estimate. However, estimations of blood velocities are of importance in characterizing venous disease.......001). The average of the peak velocity standard deviations (SD) were 17.0 cm/s for SDUS and 13.1 cm/s for TOUS (p venous disease providing quantitative measures...

  6. Portal vein blood flow is related to characteristics of the migrating motor complex of the gastrointestinal tract

    DEFF Research Database (Denmark)

    Qvist, Niels; Rafaelsen, Søren Rafael; Troensegaard, P.


    Objective: To measure variation in portal blood flow during the interdigestive state in relation to the migrating motor complex (MMC) in healthy volunteers. Design: Portal blood flow was measured by a duplex and colour Doppler technique with 5-min intervals during an entire MMC cycle. Total...... recording period varied from 105-180 min. Results: Median (range) blood flow during phase I, phase II and phase III of the MMC from the pooled data was 10.9 ml/min/kg (5.2-23.9), 15.5 ml/min/kg (4.1-38.1) and 18.9ml/min/kg (5.4-46.5), respectively; the difference between these figures was significant (P.... Conclusion: Blood flow in the portal vein varies with the characteristics of the MMC, a relationship which must be considered in future studies in health and disease....

  7. The effects of squat exercises in postures for toilet use on blood flow velocity of the leg vein. (United States)

    Eom, Jun Ho; Chung, Sin Ho; Shim, Jae Hun


    [Purpose] The purpose of this study was to identify the effects of squat exercises performed in toilet-using postures on the blood flow velocity of the lower extremities for the prevention of deep vein thrombosis. [Subjects] The subjects were 28 students who were attending B University in Cheonan. They were divided into a group of 14 subjects of sitting toilet users and a group of 14 subjects of squat toilet users. [Methods] The subjects performed squat exercises in different toilet-using postures and we investigated the changes in blood flow velocity. [Results] The variations in blood flow velocities before and after the exercises showed significant differences in both groups but the differences between the two groups were not significant. [Conclusion] Based on the results of this study, we consider squat exercises are effective at improving the variation in lower-extremity blood flow velocity when using a toilet.

  8. The effect of catheter to vein ratio on blood flow rates in a simulated model of peripherally inserted central venous catheters. (United States)

    Nifong, Thomas P; McDevitt, Timothy J


    Catheter-related thrombosis is a common complication in all anatomic sites, especially when smaller veins of the upper extremity are considered. It is presumed that the presence of a catheter within the lumen of a vein will decrease flow and potentially create stasis, and clinical data suggest that the size of the catheter impacts thrombosis rates. We sought to determine, both mathematically and experimentally, the impact of catheters on fluid flow rates. We used fluid mechanics to calculate relative flow rates as a function of the ratio of the catheter to vein diameters. We also measured the flow rate of a blood analyte solution in an annular flow model using diameters that simulate the size of upper extremity veins and commonly used peripherally inserted central catheters (PICCs). We compared each of the derived relative flow rates to the experimentally determined ones for three cylinder sizes and found a correlation of r(2) = 0.90. We also confirmed that the decrease in fluid flow rate with each successive catheter size is statistically significant (P centrally located obstruction. Assuming that blood flow in veins behaves in a similar manner to our models, PICCs, in particular, may substantially decrease venous flow rates by as much as 93%.

  9. A Study on Effects of the Transient Compression by Tightly Tied Necktie on Blood Flow in the Internal Jugular Veins Using 2D-PC MRA

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    Kim, Keung Sik; Chung, Tae Sub; Lee, Bum Soo [Dept. of Diagnostic Radiology, Yongdong Severance Hospital Yensei University, Seoul (Korea, Republic of); Park, In Kook [Dept. of Biology, Dongguk University, Seoul (Korea, Republic of); Kim, Hyun Soo [Dept. of Biology, Kangwon National University, Chuncheon (Korea, Republic of); Yoo, Beong Gyu [Dept. of Radiotechnology, Wonkwang Health Science College, Iksan (Korea, Republic of)


    The 25 healthy male volunteers aged from 20 to 50 years old have been employed in this study. 2D-PC MRA was performed to measure the velocity of the blood flow in the internal carotid artery and internal jugular veins using 3.0T MRI Whole body (signa VH/i GE). ECTRICKS-CEMRA was performed to evaluate the pattern of blood circulation from internal carotid artery to internal jugular vein. Using 2D-PC MRA, the cross-section of the 4th and 5th cervical discs was scanned with 24 cm FOV. Then the speed of blood flow was measured for internal carotid artery and internal jugular vein when the subject wears a necktie tightly and no tie. The average of maximum velocity of internal carotid arteries without a necktie was 72.13 cm/sec in the right side and 74.96 cm/sec in the left side (average 73.54 cm/sec in both sides) while the average of maximum velocity of internal jugular veins without a necktie was -34.45 cm/sec in the right side and -24.99 cm/sec in the left side (-29.72 cm/sec in both sides). However, when wearing a necktie tightly, the average of maximum velocity of internal carotid arteries was 61.35 cm/sec in the right side and 65.19 cm/sec in the left side (average 63.27 cm/sec in both sides) while the average of maximum velocity of internal jugular veins was -22.14 cm/sec in the right side and -17.93 cm/sec in the left side (-20.03 cm/sec in both sides). With the necktie tightly knotted, the average blood flow speed of both internal carotid arteries slightly decreased to 86% (63.27/73.54 cm/sec) compared to no tie case in which both internal jugularveins significantly went down to 67% (-20.03/-29.72 cm/sec). Thus it is suggested that wearing a necktie affects the circulation of internal jugular veins (33% decrease in blood flow speed) more significantly than that of internal carotid artery (14% decrease in blood flow speed). Without a necktie, ECTRICKS-CEMRA showed natural blood circulation patterns of internal carotid arteries and internal jugular veins without

  10. Influence of Acute Jugular Vein Compression on the Cerebral Blood Flow Velocity, Pial Artery Pulsation and Width of Subarachnoid Space in Humans


    Frydrychowski, Andrzej F.; Winklewski, Pawel J.; Guminski, Wojciech


    PURPOSE: The aim of this study was to assess the effect of acute bilateral jugular vein compression on: (1) pial artery pulsation (cc-TQ); (2) cerebral blood flow velocity (CBFV); (3) peripheral blood pressure; and (4) possible relations between mentioned parameters. METHODS: Experiments were performed on a group of 32 healthy 19-30 years old male subjects. cc-TQ and the subarachnoid width (sas-TQ) were measured using near-infrared transillumination/backscattering sounding (NIR-T/BSS), CBFV i...

  11. Femoral to cerebral arterial blood flow redistribution and femoral vein distension during orthostatic tests after 4 days in the head-down tilt position or confinement. (United States)

    Arbeille, P; Sigaudo, D; Pavy Le Traon, A; Herault, S; Porcher, M; Gharib, C


    The first objective of this study was to confirm that 4 days of head-down tilt (HDT) were sufficient to induce orthostatic intolerance, and to check if 4 days of physical confinement may also induce orthostatic intolerance. Evidence of orthostatic intolerance during tilt-up tests was obtained from blood pressure and clinical criteria. The second objective was to quantify the arterial and venous changes associated with orthostatic intolerance and to check whether abnormal responses to the tilt test and lower body negative pressure (LBNP) may occur in the absence of blood pressure or clinical signs of orthostatic intolerance. The cerebral and lower limb arterial blood flow and vascular resistance, the flow redistribution between these two areas, and the femoral vein distension were assessed during tilt-up and LBNP by ultrasound. Eight subjects were given 4 days of HDT and, 1 month later, 4 days of physical confinement. Tilt and LBNP test were performed pre- and post-HDT and confinement. Orthostatic intolerance was significantly more frequent after HDT (63%) than after confinement (25%, P tilt-up and LBNP tests were similar pre- and post-HDT or confinement. Conversely, during both tilt and LBNP tests the femoral vascular resistances increased less (P tilt-up and LBNP, which reduced the flow redistribution in favour of the brain in all HDT subjects. Confinement did not alter significantly the haemodynamic responses to orthostatic tests. The cerebral to femoral blood flow ratio measured during LBNP was the best predictor of orthostatic intolerance.

  12. Effect of umbilical vein blood flow on perinatal outcome of fetuses with lean and/or hypo-coiled umbilical cord. (United States)

    El Behery, Manal M; Nouh, Amal A; Alanwar, Amal M; Diab, Abdalla E


    To evaluate the effect of umbilical vein (UV) blood flow measured by color-directed pulsed-wave Doppler on perinatal outcome of fetuses with lean and/or hypocoiled umbilical cord after 24 weeks of gestation. Two hundred and forty-four women with singleton fetus after 24 weeks of gestation were studied. Umbilical cord area, umbilical vessel cross-sectional area and antenatal umbilical coiling index (UCI) were calculated and compared with Doppler parameters including UV blood flow volume in ml/min/kg, UV peak systolic velocity in cm/s, and umbilical artery pulsatility index. Thirty-eight (15.5%) fetuses had lean umbilical cord (area UCI (0.17 ± 0.06 vs. 0.35 ± 0.08, P UCI and UV blood flow (r = 0.73, P < 0.001). Fetuses with lean and/or hypo-coiled umbilical cord showed a noticeable decrease in UV blood flow of sufficient magnitude that could affect fetal growth, and this could explain the higher prevalence of fetal intrapartum complications in growth-restricted fetuses.

  13. Influence of acute jugular vein compression on the cerebral blood flow velocity, pial artery pulsation and width of subarachnoid space in humans.

    Directory of Open Access Journals (Sweden)

    Andrzej F Frydrychowski

    Full Text Available PURPOSE: The aim of this study was to assess the effect of acute bilateral jugular vein compression on: (1 pial artery pulsation (cc-TQ; (2 cerebral blood flow velocity (CBFV; (3 peripheral blood pressure; and (4 possible relations between mentioned parameters. METHODS: Experiments were performed on a group of 32 healthy 19-30 years old male subjects. cc-TQ and the subarachnoid width (sas-TQ were measured using near-infrared transillumination/backscattering sounding (NIR-T/BSS, CBFV in the left anterior cerebral artery using transcranial Doppler, blood pressure was measured using Finapres, while end-tidal CO(2 was measured using medical gas analyser. Bilateral jugular vein compression was achieved with the use of a sphygmomanometer held on the neck of the participant and pumped at the pressure of 40 mmHg, and was performed in the bend-over (BOPT and swayed to the back (initial position. RESULTS: In the first group (n = 10 during BOPT, sas-TQ and pulse pressure (PP decreased (-17.6% and -17.9%, respectively and CBFV increased (+35.0%, while cc-TQ did not change (+1.91%. In the second group, in the initial position (n = 22 cc-TQ and CBFV increased (106.6% and 20.1%, respectively, while sas-TQ and PP decreases were not statistically significant (-15.5% and -9.0%, respectively. End-tidal CO(2 remained stable during BOPT and venous compression in both groups. Significant interdependence between changes in cc-TQ and PP after bilateral jugular vein compression in the initial position was found (r = -0.74. CONCLUSIONS: Acute bilateral jugular venous insufficiency leads to hyperkinetic cerebral circulation characterised by augmented pial artery pulsation and CBFV and direct transmission of PP into the brain microcirculation. The Windkessel effect with impaired jugular outflow and more likely increased intracranial pressure is described. This study clarifies the potential mechanism linking jugular outflow insufficiency with arterial small vessel cerebral

  14. Influence of acute jugular vein compression on the cerebral blood flow velocity, pial artery pulsation and width of subarachnoid space in humans. (United States)

    Frydrychowski, Andrzej F; Winklewski, Pawel J; Guminski, Wojciech


    The aim of this study was to assess the effect of acute bilateral jugular vein compression on: (1) pial artery pulsation (cc-TQ); (2) cerebral blood flow velocity (CBFV); (3) peripheral blood pressure; and (4) possible relations between mentioned parameters. Experiments were performed on a group of 32 healthy 19-30 years old male subjects. cc-TQ and the subarachnoid width (sas-TQ) were measured using near-infrared transillumination/backscattering sounding (NIR-T/BSS), CBFV in the left anterior cerebral artery using transcranial Doppler, blood pressure was measured using Finapres, while end-tidal CO(2) was measured using medical gas analyser. Bilateral jugular vein compression was achieved with the use of a sphygmomanometer held on the neck of the participant and pumped at the pressure of 40 mmHg, and was performed in the bend-over (BOPT) and swayed to the back (initial) position. In the first group (n = 10) during BOPT, sas-TQ and pulse pressure (PP) decreased (-17.6% and -17.9%, respectively) and CBFV increased (+35.0%), while cc-TQ did not change (+1.91%). In the second group, in the initial position (n = 22) cc-TQ and CBFV increased (106.6% and 20.1%, respectively), while sas-TQ and PP decreases were not statistically significant (-15.5% and -9.0%, respectively). End-tidal CO(2) remained stable during BOPT and venous compression in both groups. Significant interdependence between changes in cc-TQ and PP after bilateral jugular vein compression in the initial position was found (r = -0.74). Acute bilateral jugular venous insufficiency leads to hyperkinetic cerebral circulation characterised by augmented pial artery pulsation and CBFV and direct transmission of PP into the brain microcirculation. The Windkessel effect with impaired jugular outflow and more likely increased intracranial pressure is described. This study clarifies the potential mechanism linking jugular outflow insufficiency with arterial small vessel cerebral disease.

  15. [Portal perfusion with right gastroepiploic vein flow in liver transplant]. (United States)

    Mendoza-Sánchez, Federico; Javier-Haro, Francisco; Mendoza-Medina, Diego Federico; González-Ojeda, Alejandro; Cortés-Lares, José Antonio; Fuentes-Orozco, Clotilde

    Liver transplantation in patients with liver cirrhosis, portal vein thrombosis, and cavernous transformation of the portal vein, is a complex procedure with high possibility of liver graft dysfunction. It is performed in 2-19% of all liver transplants, and has a significantly high mortality rate in the post-operative period. Other procedures to maintain portal perfusion have been described, however there are no reports of liver graft perfusion using right gastroepiploic vein. A 20 year-old female diagnosed with cryptogenic cirrhosis, with a Child-Pugh score of 7 points (class "B"), and MELD score of 14 points, with thrombosis and cavernous transformation of the portal vein, severe portal hypertension, splenomegaly, a history of upper gastrointestinal bleeding due to oesophageal varices, and left renal agenesis. The preoperative evaluation for liver transplantation was completed, and the right gastroepiploic vein of 1-cm diameter was observed draining to the infrahepatic inferior vena cava and right suprarenal vein. An orthotopic liver transplantation was performed from a non-living donor (deceased on January 30, 2005) using the Piggy-Back technique. Portal vein perfusion was maintained using the right gastroepiploic vein, and the outcome was satisfactory. The patient was discharged 13 days after surgery. Liver transplantation was performed satisfactorily, obtaining an acceptable outcome. In this case, the portal perfusion had adequate blood flow through the right gastroepiploic vein. Copyright © 2015 Academia Mexicana de Cirugía A.C. Publicado por Masson Doyma México S.A. All rights reserved.

  16. Orbital decompression surgery and horse chestnut seed extract improved superior orbital vein blood flow in patients with thyroid-associated ophthalmopathy

    Directory of Open Access Journals (Sweden)

    Yu-Jie Wu


    Full Text Available AIM: To evaluate the efficacy and safety of orbital decomposition (OD surgery in combination with horse chestnut seed extract (HCSE, as compared to OD alone, in patients with thyroid-associated ophthalmopathy (TAO. METHODS: Sixty-two orbits from 62 TAO patients were randomly assigned to OD or OD+HCSE at 1:1 ratio (31 received OD alone, 31 received OD+HCSE. Forty-two orbits from 21 healthy subjects were used as controls. Complete ophthalmic examination and color Doppler flow imaging (CDFI were performed before surgery and 3mo post-surgery on all 62 orbits from the TAO patients. CDFI were also performed on the 42 control orbits. The effect of OD+HCSE and OD alone on TAO orbits was compared on several endpoints, including superior ophthalmic vein blood flow (SOVBF parameters, subjective assessment, soft tissue involvement, lid retraction, diplopia, eye movement restriction, degree of exophthalmos, and intraocular pressure. The control orbits were used as reference for the SOVBF parameters. RESULTS: OD surgery with or without HCSE improved SOVBF, symptoms and soft tissue involvement, decreased degree of exophthalmos and intraocular pressure in orbits of TAO patients. The OD+HCSE combination led to significantly better improvement of SOVBF than OD alone. The differences between the reductions of SOVBF in the two groups are 1.26 cm/s in max-volecity and 0.52 cm/s in min-volecity (P<0.0001. CONCLUSION: SOVBF is significantly reduced in the orbits affected with TAO, indicating that congestion may be an important factor contributing to TAO pathogenesis. OD surgery improves the SOVBF, and combination of HCSE medication and OD surgery further improved venous return than OD surgery alone.

  17. Changes in wall motion and blood flow in the outflow tract of chick embryonic hearts observed with optical coherence tomography after outflow tract banding and vitelline-vein ligation

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    Rugonyi, Sandra; Liu Aiping; Wang, Ruikang K [Division of Biomedical Engineering, Oregon Health and Science University, 3303 SW Bond Ave., CH13B, Portland, OR 97239 (United States); Shaut, Carley; Thornburg, Kent [Heart Research Center, Oregon Health and Science University, Portland, OR (United States)


    Optical coherence tomography (OCT) is a non-contact, non-invasive and high-resolution imaging technique, suited to study early cardiovascular development. Alterations in hemodynamic conditions during early development are known to lead to cardiac defects, presumably as a result of changes in cardiac biomechanics produced by the alterations. In this paper, we demonstrate the use of a spectral domain OCT in visualizing and quantifying changes in cardiac wall motion and blood-flow velocities under normal and altered hemodynamic conditions in chicken embryos at an early stage of development (Hamburger-Hamilton stage HH18, {approx}3 days of incubation), focusing on the heart outflow tract (OFT). The OCT system employed acquired simultaneously microstructural and blood-flow images at a rate of 92 frames s{sup -1}with a spatial resolution of {approx}10 {mu}m. OCT imaging allowed in vivo visualization of the OFT microstructures, e.g. the lumen, cardiac cushions and myocardium. We found that alterations in hemodynamic conditions, through OFT banding and vitelline-vein ligation, changed blood-flow velocities through the OFT, as expected. Further, OCT allowed quantification of changes in the dynamics of OFT wall motion. Our results therefore establish the utility of spectral domain OCT to study the influence of hemodynamic conditions on heart development in intact, in vivo chicken embryo models.

  18. Influence of acute jugular vein compression on the cerebral blood flow velocity, pial artery pulsation and width of subarachnoid space in humans

    National Research Council Canada - National Science Library

    Frydrychowski, Andrzej F; Winklewski, Pawel J; Guminski, Wojciech


    ...) was measured using medical gas analyser. Bilateral jugular vein compression was achieved with the use of a sphygmomanometer held on the neck of the participant and pumped at the pressure of 40 mmHg, and was performed in the bend-over (BOPT...

  19. Influence of acute jugular vein compression on the cerebral blood flow velocity, pial artery pulsation and width of subarachnoid space in humans

    National Research Council Canada - National Science Library

    Frydrychowski, Andrzej F; Winklewski, Pawel J; Guminski, Wojciech


    ...) was measured using medical gas analyser. Bilateral jugular vein compression was achieved with the use of a sphygmomanometer held on the neck of the participant and pumped at the pressure of 40 mmHg, and was performed in the bend...

  20. The pathology of facial vein blood sampling in mice

    DEFF Research Database (Denmark)

    Hansen, Ket; Harslund, Jakob le Fèvre; Bollen, Peter


    vein blood sampling. Therefore, we investigated if this technique was associated with pathological changes of the jaw region. Methods: 43 NMRI mice were subjected to facial vein blood sampling by using the lancet method during 12 months, starting at the age of 8 weeks. The mice were restrained manually......, and the tissue of the jaw was evaluated. Results: In the 23 mice, from which blood samples had been taken 2 days previously, 5 mice had no signs of gross pathological changes, whereas 12 mice had signs of minimal local subcutaneous bleeding and 6 mice had moderate local subcutaneous bleeding. No additional gross...... pathological changes were observed. In the 23 mice, from which blood samples had been taken 4 weeks earlier, no hemorrhage or signs of scar tissue formation could be observed. Histological slides are currently being processed (HE staining) and will be evaluated and discussed....

  1. Nuclide Transport and Diffusion for Vein and Fracture Flow

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    Heer, W


    Modelling radionuclide transport through crystalline rock is usually based on a small water flow in a system of narrow fractures. This flow is denoted as fracture flow. In our model, it implies planar water-conducting channels and adjacent zones of dominant matrix diffusion. According to the constitution of the rock, it can be necessary to consider additionally a vein flow being characterized by cylindrical water-conducting channels and adjacent zones of dominant matrix diffusion. Transport calculations, based on a dual porosity concept, were performed for vein as well as for fracture flow. An extensive discussion of the results provides an overview on important parameter dependencies and on the major vein flow effects. Formulae for quick estimates are given to guide quantitative interpretation of break-through curves. The discussion of analytical results for nuclide diffusion from a planar and from a cylindrical boundary backs up the comments on matrix diffusion. The following effects of vein flow onto the break-through curves are illustrative examples of useful findings: (1) The peak height can be very strongly reduced compared to fracture flow. The peak arrival time, however, is only slightly changed. (2) The asymptotic part of the tail is flatter than the well-known t{sup -3/2} decrease for fracture flow. (3) The bump at the end of the tail, generated by the limitation of the diffusion zones, is substantially larger than for fracture flow. A double-peak break-through curve, therefore, can emerge from many cases of nuclide transport. (4) Sorption on the surfaces of diffusion-accessible pores can substantially change the break-through curves. The vein to fracture flow ratios of the break-through peak data, however, remain essentially equal. This holds for the whole range of investigated retardation factors from 7 to 27'000. The investigations presented contribute to sophisticated interpretations of break-through curves and improve the physical understanding

  2. The effects of vasoactive agents on flow through saphenous vein grafts during lower-extremity peripheral vascular surgery. (United States)

    Maslow, Andrew D; Bert, Arthur; Slaiby, Jeffrey; Carney, William; Marcaccio, Edward


    The purpose of this study was to assess the effects of hemodynamic alterations on vein graft flow during peripheral vascular surgery. It was hypothesized that vasopressors can be administered without compromising flow through the vein grafts. Tertiary care center, university medical center. Randomized placebo-controlled double-blinded study. The effects of phenylephrine, epinephrine, milrinone, intravenous fluid, and placebo on newly constructed peripheral vein grafts were assessed in 60 patients (12 patients in each of 5 groups). Systemic and central hemodynamics were measured by using intra-arterial and pulmonary artery catheters. Vein graft flow was measured by using a transultrasonic flow probe (Transultrasonic Inc, Ithaca, NY). Phenylephrine increased systemic mean blood pressure (mBP) (68.2-94.0 mmHg, p < 0.01), systemic vascular resistance (SVR) (1,091-1,696 dynes x sec x cm(-5), p < 0.001), and vein graft flow (39.5-58.9 mL/min, p < 0.01), whereas cardiac output remained unchanged. Epinephrine resulted in increased cardiac output (4.4-6.9 L/min, p < 0.01) and mBP (72.7-89.1 mmHg, p < 0.01), whereas vein graft flow was reduced in 6 of 12 patients. Intravenous fluid administration resulted in a relatively smaller increase in graft flow (37.6-46.0 mL/min, p < 0.05), an increase in cardiac output, and an insignificant decrease in SVR. Other treatments had either little or no effect on vein graft flow. The study hypothesis was partly supported. Although both phenylephrine and epinephrine increased blood pressure, only the former increased vein graft flow in all patients. In conjunction with increases in graft flow after fluid administration, these data suggest that factors affecting vein graft flow are not just simply related to systemic hemodynamics.

  3. Effect of obstructive jaundice on hepatic hemodynamics: use of Sonazoid-enhanced ultrasonography in a prospective study of the blood flow balance between the hepatic portal vein and hepatic artery. (United States)

    Wakui, Noritaka; Takeda, Yuki; Nishinakagawa, Shuta; Ueki, Nobuo; Otsuka, Takafumi; Oba, Nobuyuki; Hashimoto, Hiroshi; Kamiyama, Naohisa; Sumino, Yasukiyo; Kojima, Tatsuya


    To prospectively clarify the effects of obstructive jaundice (OJ) on hepatic hemodynamics using contrast-enhanced ultrasonography (US). Subjects comprised 14 patients admitted to our hospital for OJ between April 2013 and March 2014. Contrast-enhanced US was performed using the LOGIQ E9 ultrasound device during the jaundice phase, before biliary drainage, and again after improvement of jaundice. After injecting the Sonazoid contrast agent, contrast dynamics were recorded in the right kidney and liver segments 5 or 6. Prototype software was used to calculate mean arrival time (AT) of the contrast agent in the liver parenchyma. Statistical analysis was performed to compare the mean AT in the jaundice and improved jaundice phases. We were unable to follow up three of the 14 patients after biliary drainage; thus, we included 11 patients for further analysis. The mean AT of the contrast agent was 2.0 ± 1.8 and 6.1 ± 2.3 s in the jaundice and improved jaundice phases, respectively, showing significantly shorter AT in the jaundice phase (p = 0.0033). Our findings indicate that OJ may influence the blood flow balance between the hepatic portal vein and hepatic artery.

  4. Docosahexaenoic acid inhibits the adhesion of flowing neutrophils to cytokine stimulated human umbilical vein endothelial cells. (United States)

    Yates, Clara M; Tull, Samantha P; Madden, Jackie; Calder, Philip C; Grimble, Robert F; Nash, Gerard B; Rainger, G Ed


    The (n-3) PUFA, DHA, is widely thought to posses the ability to modulate the inflammatory response. However, its modes of interaction with inflammatory cells are poorly understood. In particular, there are limited data on the interactions of DHA with vascular endothelium, the cells that regulate the traffic of leukocytes from the blood into inflamed tissue. Using human umbilical vein endothelial cells (EC) cultured in a flow-based adhesion assay and activated with TNFα, we tested whether supplementing human umbilical vein EC with physiologically achievable concentrations of DHA would inhibit the recruitment of flowing neutrophils. DHA caused a dose-dependent reduction in neutrophil recruitment to the EC surface, although cells that became adherent were activated and could migrate across the human umbilical vein EC monolayer normally. Using EPA as an alternative supplement had no effect on the levels of neutrophil adhesion in this assay. Analysis of adhesion receptor expression by qPCR demonstrated that DHA did not alter the transcriptional activity of human umbilical vein EC. However, DHA did significantly reduce E-selectin expression at the human umbilical vein EC surface without altering the total cellular pool of this adhesion receptor. Thus, we have identified a novel mechanism by which DHA alters the trafficking of leukocytes during inflammation and demonstrate that this involves disruption of intracellular transport mechanisms used to present adhesion molecules on the surface of cytokine-stimulated EC.

  5. Blood flow and microgravity (United States)

    Bureau, Lionel; Coupier, Gwennou; Dubois, Frank; Duperray, Alain; Farutin, Alexander; Minetti, Christophe; Misbah, Chaouqi; Podgorski, Thomas; Tsvirkun, Daria; Vysokikh, Mikhail


    The absence of gravity during space flight can alter cardio-vascular functions partially due to reduced physical activity. This affects the overall hemodynamics, and in particular the level of shear stresses to which blood vessels are submitted. Long-term exposure to space environment is thus susceptible to induce vascular remodeling through a mechanotransduction cascade that couples vessel shape and function with the mechanical cues exerted by the circulating cells on the vessel walls. Central to such processes, the glycocalyx - i.e. the micron-thick layer of biomacromolecules that lines the lumen of blood vessels and is directly exposed to blood flow - is a major actor in the regulation of biochemical and mechanical interactions. We discuss in this article several experiments performed under microgravity, such as the determination of lift force and collective motion in blood flow, and some preliminary results obtained in artificial microfluidic circuits functionalized with endothelium that offer interesting perspectives for the study of the interactions between blood and endothelium in healthy condition as well as by mimicking the degradation of glycocalyx caused by long space missions. A direct comparison between experiments and simulations is discussed. xml:lang="fr"

  6. In vivo evaluation of femoral blood flow measured with magnetic resonance

    DEFF Research Database (Denmark)

    Henriksen, O; Ståhlberg, F; Thomsen, C


    Quantitative measurements of blood flow based on magnetic resonance imaging (MRI) using conventional multiple spin echo sequences were evaluated in vivo in healthy young volunteers. Blood flow was measured using MRI in the femoral vein. The initial slope of the multiple spin echo decay curve...... that in vivo blood flow measurements made with MRI based on wash-out effects, commonly used in multiple spin echo imaging, do not give reliable absolute values for blood flow in the femoral artery or vein......., corrected for the T2 decay of non-flowing blood was used to calculate the blood flow. As a reference, the blood flow in the femoral artery was measured simultaneously with an invasive indicator dilution technique. T2 of non-flowing blood was measured in vivo in popliteal veins during regional circulatory...

  7. On the consistency of flow rate color Doppler assessment for the internal jugular vein

    Directory of Open Access Journals (Sweden)

    Francesco Sisini


    Full Text Available Color Doppler methodology to assess the vessel blood flow rate is based on the time averaged velocity of the blood measured in the longitudinal plane and the cross sectional area measurement taken either in the longitudinal plane, by assuming circular cross sectional area, or in the transversal plane. The measurement option in longitudinal plane is based on the assumption of circular cross sectional area, while the transversal one needs to evaluate both time-averaged velocity and cross sectional area in the same vessel point. A precise and validated assessment methodology is still lacking. Four healthy volunteers underwent internal jugular vein colour Doppler scanning. The cross sectional area was assessed by means of B-mode imaging in the transversal plane all along the vessel cervical course. During this assessment, cross sectional area, major and minor axis of the vessel were measured and recorded. The distance between the internal jugular vein wall and the skin surface were measured together with the intra-luminal diameter and statistically correlated with the cross sectional area data. The internal jugular vein cross sectional area measured on the transversal plane were significantly different from the cross sectional area calculated using the assumption of circular shape. The intra-luminal distance showed high correlation with the measured cross sectional area. The proper anatomical point in the cross sectional area transversal measurement can be identified by using the internal jugular vein intra-luminal distance as landmark.

  8. Modelling and simulation of flow and agglomeration in deep veins valves using discrete multi physics. (United States)

    Ariane, M; Wen, W; Vigolo, D; Brill, A; Nash, F G B; Barigou, M; Alexiadis, A


    The hemodynamics in flexible deep veins valves is modelled by means of discrete multi-physics and an agglomeration algorithm is implemented to account for blood accrual in the flow. Computer simulations of a number of valves typologies are carried out. The results show that the rigidity and the length of the valve leaflets play a crucial role on both mechanical stress and stagnation in the flow. Rigid and short membranes may be inefficient in preventing blood reflux, but reduce the volume of stagnant blood potentially lowering the chances of thrombosis. Additionally, we also show that in venous valves, cell agglomeration is driven by stagnation rather than mechanical stress. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Deep Vein Thrombosis (DVT) / Pulmonary Embolism (PE) - Blood Clot Forming in a Vein (United States)

    ... Facebook Tweet Share Compartir Deep Vein Thrombosis and Pulmonary Embolism (DVT/PE) are often underdiagnosed and serious, but ... bloodstream to the lungs, causing a blockage called pulmonary embolism (PE). If the clot is small, and with ...

  10. Portal flow into the liver through veins at the site of biliary-enteric anastomosis. (United States)

    Hashimoto, M; Heianna, J; Yasuda, K; Tate, E; Watarai, J; Shibata, S; Sato, T; Yamamoto, Y


    The aim of this study was to establish the role played by jejunal veins in hepatopetal flow after biliary-enteric anastomosis and to evaluate the helical CT features of hepatopetal flow through the anastomosis. We retrospectively analyzed helical CT images of the liver in 31 patients with biliary-enteric anastomosis who underwent hepatic angiography with (n=13) or without (n=18) CT arterial portography within 2 weeks of the CT examination during the last 4 years. Arterial portography showed hepatopetal flow through small vessels located (communicating veins) between the elevated jejunal veins and the intrahepatic portal branches in two (9%) of 22 patients with a normal portal system. Helical CT showed focal parenchymal enhancement around the anastomosis in these two patients. All nine patients with extrahepatic portal vein occlusion (100%) had hepatopetal flow through the anastomosis, and four of the nine had decreased portal flow. CT revealed small communicating veins in two of these four patients. In five patients with normal portal perfusion despite extrahepatic portal vein occlusion, CT detected dilated communicating veins and elevated jejunal veins. The presence of communicating veins and/or focal parenchymal enhancement around the anastomosis indicates hepatopetal flow through the elevated jejunal veins.

  11. In vivo evaluation of femoral blood flow measured with magnetic resonance

    DEFF Research Database (Denmark)

    Henriksen, O; Ståhlberg, F; Thomsen, C


    Quantitative measurements of blood flow based on magnetic resonance imaging (MRI) using conventional multiple spin echo sequences were evaluated in vivo in healthy young volunteers. Blood flow was measured using MRI in the femoral vein. The initial slope of the multiple spin echo decay curve......, corrected for the T2 decay of non-flowing blood was used to calculate the blood flow. As a reference, the blood flow in the femoral artery was measured simultaneously with an invasive indicator dilution technique. T2 of non-flowing blood was measured in vivo in popliteal veins during regional circulatory...... arrest. The mean T2 of non-flowing blood was found to be 105 +/- 31 ms. The femoral blood flow ranged between 0 and 643 ml/min measured with MRI and between 280 and 531 ml/min measured by the indicator dilution technique. There was thus poor agreement between the two methods. The results indicate...

  12. Local Control of Blood Flow (United States)

    Clifford, Philip S.


    Organ blood flow is determined by perfusion pressure and vasomotor tone in the resistance vessels of the organ. Local factors that regulate vasomotor tone include myogenic and metabolic autoregulation, flow-mediated and conducted responses, and vasoactive substances released from red blood cells. The relative importance of each of these factors…

  13. Blood pooling in extrathoracic veins after glossopharyngeal insufflation

    DEFF Research Database (Denmark)

    Mijacika, Tanja; Frestad, Daria; Kyhl, Kasper


    divers in a sub-study. Results: After GPI, pulmonary volume increased by 0.8 ± 0.6 L above total lung capacity. The diameter of the superior caval (by 36 ± 17%) and intrathoracic part of the inferior caval vein decreased (by 21 ± 16%), while the diameters of the internal jugular (by 53 ± 34%), hepatic......Purpose: Trained breath-hold divers hyperinflate their lungs by glossopharyngeal insufflation (GPI) to prolong submersion time and withstand lung collapse at depths. Pulmonary hyperinflation leads to profound hemodynamic changes. Methods: Thirteen divers performed preparatory breath-holds followed...... (by 28 ± 40%), abdominal part of the inferior caval (by 28 ± 28%), and femoral veins (by 65 ± 50%) all increased (P volume of the internal jugular, the hepatic, the abdominal part of the inferior caval vein, and the combined common iliac and femoral veins increased by 145 ± 115, 80 ± 88...

  14. Endovascular blood flow measurement system (United States)

    Khe, A. K.; Cherevko, A. A.; Chupakhin, A. P.; Krivoshapkin, A. L.; Orlov, K. Yu


    In this paper an endovascular measurement system used for intraoperative cerebral blood flow monitoring is described. The system is based on a Volcano ComboMap Pressure and Flow System extended with analogue-to-digital converter and PC laptop. A series of measurements performed in patients with cerebrovascular pathologies allows us to introduce “velocity-pressure” and “flow rate-energy flow rate” diagrams as important characteristics of the blood flow. The measurement system presented here can be used as an additional instrument in neurosurgery for assessment and monitoring of the operation procedure. Clinical data obtained with the system are used for construction of mathematical models and patient-specific simulations. The monitoring of the blood flow parameters during endovascular interventions was approved by the Ethics Committee at the Meshalkin Novosibirsk Research Institute of Circulation Pathology and included in certain surgical protocols for pre-, intra- and postoperative examinations.

  15. Hyperhomocysteinemia decreases bone blood flow

    Directory of Open Access Journals (Sweden)

    Neetu T


    Full Text Available Neetu Tyagi*, Thomas P Vacek*, John T Fleming, Jonathan C Vacek, Suresh C TyagiDepartment of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, KY, USA *These authors have equal authorshipAbstract: Elevated plasma levels of homocysteine (Hcy, known as hyperhomocysteinemia (HHcy, are associated with osteoporosis. A decrease in bone blood flow is a potential cause of compromised bone mechanical properties. Therefore, we hypothesized that HHcy decreases bone blood flow and biomechanical properties. To test this hypothesis, male Sprague–Dawley rats were treated with Hcy (0.67 g/L in drinking water for 8 weeks. Age-matched rats served as controls. At the end of the treatment period, the rats were anesthetized. Blood samples were collected from experimental or control rats. Biochemical turnover markers (body weight, Hcy, vitamin B12, and folate were measured. Systolic blood pressure was measured from the right carotid artery. Tibia blood flow was measured by laser Doppler flow probe. The results indicated that Hcy levels were significantly higher in the Hcy-treated group than in control rats, whereas vitamin B12 levels were lower in the Hcy-treated group compared with control rats. There was no significant difference in folate concentration and blood pressure in Hcy-treated versus control rats. The tibial blood flow index of the control group was significantly higher (0.78 ± 0.09 flow unit compared with the Hcy-treated group (0.51 ± 0.09. The tibial mass was 1.1 ± 0.1 g in the control group and 0.9 ± 0.1 in the Hcy-treated group. The tibia bone density was unchanged in Hcy-treated rats. These results suggest that Hcy causes a reduction in bone blood flow, which contributes to compromised bone biomechanical properties.Keywords: homocysteine, tibia, bone density

  16. Technical note: Measurement of mammary plasma flow in sows by downstream dilution of mammary vein infused para-aminohippuric acid

    DEFF Research Database (Denmark)

    Larsen, Uffe Krogh; Storm, Adam Christian; Theil, Peter Kappel


    catheter was surgically implanted in the femoral artery, and another 2 were inserted in the right cranial mammary vein of 8 second- and third-parity sows on d 76 ± 2 SEM of gestation. On the 3rd and 17th days in milk, arterial and venous blood samples were drawn in hourly intervals from 0.5 h before until...... 6.5 h after feeding. The MPF in the right cranial mammary vein was measured by downstream dilution of infused pAH (3.0 mmol/h). Total MPF-pAH was calculated assuming that the measured flow constituted the flow from 5 out of 14 suckled glands on the basis of the anatomical structure of the mammary...

  17. Effect of Change in Portal Vein Flow Rates on Hepatic Ablations Created with a Bipolar Radiofrequency Ablation Device. (United States)

    Dodd, Gerald D; Lanctot, Anthony C; Lind, Kimberly E


    Purpose To investigate the effect of change in portal vein flow rates on the size and shape of ablations created by a bipolar radiofrequency (RF) ablation device. Materials and Methods This study was exempt from institutional animal care and use committee review. An in vitro bovine liver model perfused with autologous blood via the portal vein at three flow rates (60, 80, 100 mL/min per 100 g of liver) was used. Four ablations, two bipolar and two monopolar (control probe), were made in each of five livers perfused at each flow rate. Short- and long-axis diameters were measured from gross specimens, and volume and sphericity index were calculated for each ablation. A general linear mixed model accounting for correlation within the liver was used to evaluate the effects of flow on ablations. Analyses were performed by using software. Results There was no significant difference in the size or shape of ablations created by the bipolar device at the different flow rates (P > .05 for all outcomes). The monopolar device demonstrated the expected inverse association between ablation size and change in flow (P flow rates does not have a statistically significant effect on the size or shape of ablations created by the bipolar RF ablation device tested. (©) RSNA, 2016.

  18. Single versus duplicate blood samples in ACTH stimulated adrenal vein sampling

    NARCIS (Netherlands)

    Dekkers, T.; Arntz, M.; Wilt, G.J. van der; Schultze Kool, L.J.; Sweep, F.C.; Hermus, A.R.M.M.; Lenders, J.W.M.; Deinum, J.


    BACKGROUND: Adrenal vein sampling (AVS) is the preferred test for subtyping primary aldosteronism. However, the procedure is technically demanding and costly. In AVS it is common practice to take duplicate blood samples at each location. In this paper we explore whether a single sample procedure

  19. Infrared Cephalic-Vein to Assist Blood Extraction Tasks: Automatic Projection and Recognition (United States)

    Lagüela, S.; Gesto, M.; Riveiro, B.; González-Aguilera, D.


    Thermal infrared band is not commonly used in photogrammetric and computer vision algorithms, mainly due to the low spatial resolution of this type of imagery. However, this band captures sub-superficial information, increasing the capabilities of visible bands regarding applications. This fact is especially important in biomedicine and biometrics, allowing the geometric characterization of interior organs and pathologies with photogrammetric principles, as well as the automatic identification and labelling using computer vision algorithms. This paper presents advances of close-range photogrammetry and computer vision applied to thermal infrared imagery, with the final application of Augmented Reality in order to widen its application in the biomedical field. In this case, the thermal infrared image of the arm is acquired and simultaneously projected on the arm, together with the identification label of the cephalic-vein. This way, blood analysts are assisted in finding the vein for blood extraction, especially in those cases where the identification by the human eye is a complex task. Vein recognition is performed based on the Gaussian temperature distribution in the area of the vein, while the calibration between projector and thermographic camera is developed through feature extraction and pattern recognition. The method is validated through its application to a set of volunteers, with different ages and genres, in such way that different conditions of body temperature and vein depth are covered for the applicability and reproducibility of the method.

  20. Cerebral blood-flow tomography

    DEFF Research Database (Denmark)

    Lassen, N A; Henriksen, L; Holm, S


    . The Xe-133 flow maps are essentially based on the average Xe-133 concentration over the initial 2 min during and after an inhalation of the inert gas lasting 1 min. These maps agreed very well with the early IMP maps obtained over the initial 10 min following an i.v. bolus injection. The subsequent IMP......, and with low radiation exposure to patient and personnel. On the other hand, IMP gives an image of slightly higher resolution. It also introduces a new class of iodinated brain-seeking compounds allowing, perhaps, imaging of other functions more important than mere blood flow....

  1. Ocular Blood Flow Autoregulation Mechanisms and Methods

    Directory of Open Access Journals (Sweden)

    Xue Luo


    Full Text Available The main function of ocular blood flow is to supply sufficient oxygen and nutrients to the eye. Local blood vessels resistance regulates overall blood distribution to the eye and can vary rapidly over time depending on ocular need. Under normal conditions, the relation between blood flow and perfusion pressure in the eye is autoregulated. Basically, autoregulation is a capacity to maintain a relatively constant level of blood flow in the presence of changes in ocular perfusion pressure and varied metabolic demand. In addition, ocular blood flow dysregulation has been demonstrated as an independent risk factor to many ocular diseases. For instance, ocular perfusion pressure plays key role in the progression of retinopathy such as glaucoma and diabetic retinopathy. In this review, different direct and indirect techniques to measure ocular blood flow and the effect of myogenic and neurogenic mechanisms on ocular blood flow are discussed. Moreover, ocular blood flow regulation in ocular disease will be described.

  2. Isolation of endothelial colony-forming cells from blood samples collected from the jugular and cephalic veins of healthy adult horses. (United States)

    Sharpe, Ashley N; Seeto, Wen J; Winter, Randolph L; Zhong, Qiao; Lipke, Elizabeth A; Wooldridge, Anne A


    OBJECTIVE To evaluate optimal isolation of endothelial colony-forming cells (ECFCs) from peripheral blood of horses. SAMPLE Jugular and cephalic venous blood samples from 17 adult horses. PROCEDURES Each blood sample was divided; isolation was performed with whole blood adherence (WBA) and density gradient centrifugation (DGC). Isolated cells were characterized by uptake of 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate-labeled acetylated low-density lipoprotein (DiI-Ac-LDL), vascular tubule formation, and expression of endothelial (CD34, CD105, vascular endothelial growth factor receptor-2, and von Willebrand factor) and hematopoietic (CD14) cell markers by use of indirect immunofluorescence assay (IFA) and flow cytometry. RESULTS Colonies with cobblestone morphology were isolated from 15 of 17 horses. Blood collected from the cephalic vein yielded colonies significantly more often (14/17 horses) than did blood collected from the jugular vein (8/17 horses). Of 14 cephalic blood samples with colonies, 13 were obtained with DGC and 8 with WBA. Of 8 jugular blood samples with colonies, 8 were obtained with DGC and 4 with WBA. Colony frequency (colonies per milliliter of blood) was significantly higher for cephalic blood samples and samples isolated with DGC. Cells formed vascular tubules, had uptake of DiI-Ac-LDL, and expressed endothelial markers by use of IFA and flow cytometry, which confirmed their identity as ECFCs. CONCLUSIONS AND CLINICAL RELEVANCE Maximum yield of ECFCs was obtained for blood samples collected from both the jugular and cephalic veins and use of DGC to isolate cells. Consistent yield of ECFCs from peripheral blood of horses will enable studies to evaluate diagnostic and therapeutic uses.

  3. The effects of fenoldopam on coronary conduit blood flow after coronary artery bypass graft surgery.

    LENUS (Irish Health Repository)

    Halpenny, M


    OBJECTIVE: To quantify the effects of fenoldopam, 0.1 microg\\/kg\\/min, on left internal mammary artery (LIMA) and saphenous vein blood flow after coronary anastomosis. DESIGN: Prospective, randomized, double-blind, placebo-controlled trial. SETTING: University teaching hospital, single institution. PARTICIPANTS: Thirty-one American Society of Anesthesiologists III patients undergoing elective coronary revascularization. INTERVENTIONS: A perivascular ultrasonic flow probe (Linton Instrumentation, Norfolk, UK) was placed around the LIMA and saphenous vein graft after coronary anastomosis. MEASUREMENTS AND MAIN RESULTS: Immediately before and at 5-minute intervals for 15 minutes after starting the infusion, blood flow was measured in the LIMA and one saphenous vein graft using a transit time ultrasonic flow probe. Heart rate, blood pressure, and central venous pressure were documented at these time points. Administration of fenoldopam, 0.1 microg\\/kg\\/min, did not alter heart rate or blood pressure. A small, nonsignificant increase in LIMA blood flow occurred during the 15-minute study period (30 +\\/- 12 to 35 +\\/- 10 mL\\/min) in patients who received fenoldopam. No significant changes occurred in the placebo group. CONCLUSIONS: The findings indicate that fenoldopam, 0.1 microg\\/kg\\/min, did not influence coronary conduit blood flow to a clinically significant extent. The small increase in LIMA blood flow may be of greater importance in high-risk patients or in the prevention of coronary arterial spasm.

  4. Accurate perioperative flow measurement of the portal vein and hepatic and renal artery: A role for preoperative MRI?

    Energy Technology Data Exchange (ETDEWEB)

    Vermeulen, Mechteld A.R., E-mail: [Department of Surgery, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Ligthart-Melis, Gerdien C., E-mail: [Department of Internal Medicine, Dietetics and Nutritional Sciences, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Buijsman, René, E-mail: [Department of Surgery, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Siroen, Michiel P.C., E-mail: [Department of Surgery, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Poll, Marcel C.G. van de, E-mail: [Department of Surgery, Maastricht University Medical Center, P.O. Box 5800, 6202 AZ Maastricht (Netherlands); Boelens, Petra G., E-mail: [Department of Surgery, Maastricht University Medical Center, P.O. Box 5800, 6202 AZ Maastricht (Netherlands); Dejong, Cornelis H.C., E-mail: [Department of Surgery, Maastricht University Medical Center, P.O. Box 5800, 6202 AZ Maastricht (Netherlands); Schaik, Cors van, E-mail: [Department of Radiology, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Hofman, Mark B.M., E-mail: [Department of Physics and Medical Technology, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands); Leeuwen, Paul A.M. van, E-mail: [Department of Surgery, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam (Netherlands)


    Background: Quantification of abdominal blood flow is essential for a variety of gastrointestinal and hepatic topics such as liver transplantation or metabolic flux measurement, but those need to be performed during surgery. It is not clear whether Duplex Doppler Ultrasound during surgery or MRI before surgery is the tool to choose. Objective: To examine whether preoperative evaluation of abdominal blood flow using MRI could prove to be a useful and reliable alternative for the perioperative sonographic approach. Methods: In this study portal and renal venous flow and hepatic arterial flow were sequentially quantified by preoperative MRI, preoperative and perioperative Duplex Doppler Ultrasound (DDUS). 55 Patients scheduled for major abdominal surgery were studied and methods and settings were compared. Additionally, average patient population values were compared. Results: Mean (±SD) plasmaflow measured by perioperative DDUS, preoperative DDUS and MRI, respectively was 433 ± 200/423 ± 162/507 ± 96 ml/min (portal vein); 96 ± 70/74 ± 41/108 ± 91 ml/min (hepatic artery); 248 ± 139/201 ± 118/219 ± 69 ml/min (renal vein). No differences between the different settings of DDUS measurement were detected. Equality of mean was observed for all measurements. Bland Altman Plots showed widespread margins. Hepatic arterial flow measurements correlated with each other, but portal and renal venous flow correlations were absent. Conclusions: Surgery and method (DDUS vs. MRI) do not affect mean flow values. Individual comparison is restricted due to wide range in measurements. Since MRI proves to be more reliable with respect to inter-observer variability, we recommend using mean MRI results in experimental setups.

  5. Liver volume, portal vein flow, and clearance of indocyanine green and antipyrine in hyperthyroidism before and after antithyroid treatment

    DEFF Research Database (Denmark)

    Andersen, Vibeke; Sonne, J; Court-Payen, M


    The aim of the study was to examine liver volume, portal vein flow, and indocyanine green (ICG) and antipyrine clearance in hyperthyroidism before and after antithyroid drug treatment.......The aim of the study was to examine liver volume, portal vein flow, and indocyanine green (ICG) and antipyrine clearance in hyperthyroidism before and after antithyroid drug treatment....

  6. Vector and Doppler Ultrasound Velocities Evaluated in a Flow Phantom and the Femoropopliteal Vein

    DEFF Research Database (Denmark)

    Bechsgaard, Thor; Hansen, Kristoffer Lindskov; Brandt, Andreas Hjelm


    Ultrasound is used for evaluating the veins of the lower extremities. Operator and angle dependency limit spectral Doppler ultrasound (SDUS). The aim of the study was to compare peak velocity measurements in a flow phantom and the femoropopliteal vein of 20 volunteers with the angle-independent v......Ultrasound is used for evaluating the veins of the lower extremities. Operator and angle dependency limit spectral Doppler ultrasound (SDUS). The aim of the study was to compare peak velocity measurements in a flow phantom and the femoropopliteal vein of 20 volunteers with the angle......-independent vector velocity technique vector flow imaging (VFI) and SDUS. In the flow phantom, VFI underestimated velocity (p = 0.01), with a lower accuracy of 5.5% (p = 0.01) and with no difference in precision, that is, error factor, compared with SDUS (VFI: 1.02 vs. SDUS: 1.02, p = 0.58). In vivo, VFI estimated...

  7. Fixed volume particle trace emission for the analysis of left atrial blood flow using 4D Flow MRI. (United States)

    Gaeta, Stephen; Dyverfeldt, Petter; Eriksson, Jonatan; Carlhäll, Carl-Johan; Ebbers, Tino; Bolger, Ann F


    4D Flow MRI has been used to quantify normal and deranged left ventricular blood flow characteristics on the basis of functionally distinct flow components. However, the application of this technique to the atria is challenging due to the presence of continuous inflow. This continuous inflow necessitates plane-based emission of particle traces from the inlet veins, leading to particles that represents different amounts of blood, and related quantification errors. The purpose of this study was to develop a novel fixed-volume approach for particle tracing and employ this method to develop quantitative analysis of 4D blood flow characteristics in the left atrium. 4D Flow MRI data were acquired during free-breathing using a navigator-gated gradient-echo sequence in three volunteers at 1.5T. Fixed-volume particle traces emitted from the pulmonary veins were used to visualize left atrial blood flow and to quantitatively separate the flow into two functionally distinct flow components: Direct flow=particle traces that enter and leave the atrium in one heartbeat, Retained flow=particle traces that enter the atrium and remains there for one cardiac cycle. Flow visualization based on fixed-volume traces revealed that, beginning in early ventricular systole, flow enters the atrium and engages with residual blood volume to form a vortex. In early diastole during early ventricular filling, the organized vortical flow is extinguished, followed by formation of a second transient atrial vortex. Finally, in late diastole during atrial contraction, a second acceleration of blood into the ventricle is seen. The direct and retained left atrial flow components were between 44 and 57% and 43-56% of the stroke volume, respectively. In conclusion, fixed-volume particle tracing permits separation of left atrial blood flow into different components based on the transit of blood through the atrium. Copyright © 2017. Published by Elsevier Inc.

  8. Meal-induced changes in splanchnic blood flow and oxygen uptake in middle-aged healthy humans

    DEFF Research Database (Denmark)

    Madsen, Jan Lysgård; Søndergaard, SB; Møller, Søren


    healthy men (52-76 years). Splanchnic blood flow was measured during hepatic vein catheterization by indirect Fick principle with indocyanine green as the indicator. Splanchnic oxygen uptake was calculated from splanchnic blood flow and the arteriovenous oxygen difference. RESULTS: The meal induced...

  9. Garden City Vein Complex, Gale Crater, Mars: Implications for Late Diagenetic Fluid Flow (United States)

    Kronyak, R. E.; Kah, L. C.; Blaney, D. L.; Sumner, D. Y.; Fisk, M. R.; Rapin, W.; Nachon, M.; Mangold, N.; Grotzinger, J. P.; Wiens, R. C.


    Calcium sulfate filled fractures are observed in nearly all stratigraphic units encountered by the Mars Science Laboratory (MSL) Curiosity rover. The mm-scale of veins, however, provides little evidence for emplacement style. From sols 924-949, Curiosity observed a vein rich outcrop called Garden City, which shows variation in both thickness and complexity of veins. Extensive Mastcam and MAHLI imaging was conducted across the outcrop to provide textural detail that can be related to emplacement mechanisms. Additionally, Curiosity collected geochemical data on 17 ChemCam targets and 7 APXS targets, shedding light on the composition and variety of potential vein fluids. The Garden City vein system records (1) the presence of distinct dark-toned and light-toned (calcium sulfate) mineralization, and (2) the presence of laminated, epitaxial, and brecciated fabrics that suggest multiple emplacement modes. Dark-toned mineralization is observed as erosionally resistant ridges predominantly along fracture walls. Although erosional resistance may reflect the permeability of host rock to fracture-borne fluids, at Garden City, laminated textures suggest that at least some mineralization may have occurred as fracture-fill. Light-toned mineralization often bisects dark-toned material, indicating re-use of fluid pathways. Light-toned veinlets permeate fracture walls, and the largest veins entrain host rock and dark-toned material within calcium sulfate matrix. Such brecciation indicates high forces associated with fluid expulsion. Elsewhere, linear patterns occur broadly perpendicular to fracture walls, and are interpreted to represent epitaxial crystal growth, suggesting lower flow rates and fluid flow pressures within the fracture system. Together these observations indicate multiple episodes of fluid flow in the Gale Crater system.

  10. Regulation of the skeletal muscle blood flow in humans

    DEFF Research Database (Denmark)

    Mortensen, Stefan; Saltin, Bengt


    hyperaemia whereas the role of ATP remains uncertain due to lack of specific purinergic receptor blockers for human use. The purpose of this review is to address the interaction between vasodilator systems and to discuss the multiple proposed roles of ATP in human skeletal muscle blood flow regulation......In humans, skeletal muscle blood flow is regulated by an interaction between several locally formed vasodilators including nitric oxide (NO) and prostaglandins. In plasma, ATP is a potent vasodilator that stimulates the formation of NO and prostaglandins and very importantly can offset local...... sympathetic vasoconstriction. ATP is released into plasma from erythrocytes and endothelial cells and the plasma concentration increases in both the feeding artery and the vein draining the contracting skeletal muscle. Adenosine also stimulates the formation of NO and prostaglandins, but the plasma adenosine...

  11. The role of ATP and adenosine in the control of hepatic blood flow in the rabbit liver in vivo


    Browse, Dominic J; Mathie, Robert T; Benjamin, Irving S; Alexander, Barry


    Background The role of adenosine and ATP in the regulation of hepatic arterial blood flow in the "buffer response" was studied in vitro and in a new in vivo model in the rabbit. The model achieves portal-systemic diversion by insertion of a silicone rubber prosthesis between the portal vein and inferior vena cava and avoids alterations in systemic haemodynamics. Results Hepatic arterial (HA) blood flow increased in response to reduced portal venous (PV) blood flow, the "buffer response", from...

  12. Echo-time and field strength dependence of BOLD reactivity in veins and parenchyma using flow-normalized hypercapnic manipulation.

    Directory of Open Access Journals (Sweden)

    Christina Triantafyllou

    Full Text Available While the BOLD (Blood Oxygenation Level Dependent contrast mechanism has demonstrated excellent sensitivity to neuronal activation, its specificity with regards to differentiating vascular and parenchymal responses has been an area of ongoing concern. By inducing a global increase in Cerebral Blood Flow (CBF, we examined the effect of magnetic field strength and echo-time (TE on the gradient-echo BOLD response in areas of cortical gray matter and in resolvable veins. In order to define a quantitative index of BOLD reactivity, we measured the percent BOLD response per unit fractional change in global gray matter CBF induced by inhaling carbon dioxide (CO(2. By normalizing the BOLD response to the underlying CBF change and determining the BOLD response as a function of TE, we calculated the change in R(2(* (ΔR(2(* per unit fractional flow change; the Flow Relaxation Coefficient, (FRC for 3T and 1.5T in parenchymal and large vein compartments. The FRC in parenchymal voxels was 1.76±0.54 fold higher at 3T than at 1.5T and was 2.96±0.66 and 3.12±0.76 fold higher for veins than parenchyma at 1.5T and 3T respectively, showing a quantitative measure of the increase in specificity to parenchymal sources at 3T compared to 1.5T. Additionally, the results allow optimization of the TE to prioritize either maximum parenchymal BOLD response or maximum parenchymal specificity. Parenchymal signals peaked at TE values of 62.0±11.5 ms and 41.5±7.5 ms for 1.5T and 3T, respectively, while the response in the major veins peaked at shorter TE values; 41.0±6.9 ms and 21.5±1.0 ms for 1.5T and 3T. These experiments showed that at 3T, the BOLD CNR in parenchymal voxels exceeded that of 1.5T by a factor of 1.9±0.4 at the optimal TE for each field.

  13. Postishemic Cerebral Function and Blood Flow

    Directory of Open Access Journals (Sweden)

    V. V. Aleksandrin


    Full Text Available The impact of massive blood loss on cerebral blood flow-function relationships was studied in rats in the postis-chemic period. Anxiety was examined in the raised cross-shaped labyrinth. Cerebral blood flow was registered by a laser Doppler flowmeter. One-hour massive blood flow substantially increased the level of anxiety in 75% of the rats following 7 and 20 days. There were no significant behavior changes in 25% of the animals. Experimental animals with preserved behavioral parameters showed cerebral blood flow resistance to ischemia and reperfusion while rats with increased anxiety were found to have delayed postischemic hypoperfusion. Thus, a relationship was found between the behavior of the rats and the resistance of cerebral blood flow to ischemia and reperfusion.

  14. Blood flow in ductus venosus in early uncomplicated pregnancy. (United States)

    Sodowski, Krzysztof; Cnota, Wojciech; Czuba, Bartosz; Borowski, Dariusz; Wielgos, Miroslaw; Kaminski, Pawel; Jaczyńska, Renata; Włoch, Agata; Kuka, Dorota; Zwirska-Korczala, Krystyna; Szaflik, Krzysztof


    The ductus venosus is the very important part of fetal venous circulation. It plays a central role in return of venous blood from the placenta. This unique shunt carries well-oxygenated blood from the umbilical vein through the inferior atrial inlet on its way across the foramen ovale. Using Doppler ultrasound, it is possible to assess the blood flow in fetal vessels including ductus venosus. It is observed, in animal and human studies, that the typical waveform for blood flow in ductus venosus in early pregnancy can be different depending on numerous conditions e.g. fetal karyotype. This study is performed to assess the physiologic parameters of blood flow in ductus venosus in uncomplicated early pregnancy. 404 women were examined between 11+0 and 13+6 weeks (+ days) of gestation by ultrasound. Fetal crown-rump length (CRL) was measured to assess the gestational age. The assessment of risk of fetal abnormalities was based on nuchal translucency (NT) measurement. The ductus venosus blood flow with color and spectral Doppler was obtained in all patients. The following features were assessed: pulsatility index (PI), and direction of flow (positive/negative) during atrial contraction (wave A). All cases were followed up to 22 weeks of gestation when the control scan was performed. 30 cases were excluded from the uncomplicated group due to: high risk of fetal abnormalities, fetal loss, confirmed fetal abnormalities and utero-placental pathology. 374 women were considered as uncomplicated pregnancy. In both uncomplicated and complicated groups the mean values for pulsatility index (PI) were established. The mean PI value in uncomplicated pregnancies was: 0.91 (SD +/- 0.32). No significant differences between groups were noticed. In 370 cases of uncomplicated pregnancy the A wave direction was positive but in 1.1% of cases the reverse flow in atrial contraction was observed.

  15. Global and regional brain atrophy is associated with low or retrograde facial vein flow in multiple sclerosis

    Directory of Open Access Journals (Sweden)

    Dejan Jakimovski


    Full Text Available Increased collateral facial vein (FV flow may be associated with structural damage in patients with multiple sclerosis (MS. The objective was to assess differences in FV flow and magnetic resonance imaging (MRI-derived outcomes in MS. The study included 136 MS patients who underwent neck and head vascular system examination by echo-color Doppler. Inflammatory MRI markers were assessed on a 3T MRI using a semi-automated edge detection and contouring/ thresholding technique. MRI volumetric outcomes of whole brain (WB, gray matter (GM, white matter (WM, cortex, ventricular cerebrospinal fluid (vCSF, deep gray matter (DGM, thalamus, caudate nucleus (CN, putamen, globus pallidus (GP, and hippocampus were calculated. Independent t-test and ANCOVA, adjusted for age, were used to compare groups based on FV flow quartiles. Thirty-four MS patients with FV flow ≤327.8 mL/min (lowest quartile had significantly lower WB (P327.8 mL/min (higher quartiles. There were no differences in T1-, T2- and gadolinium- enhancing lesion volumes between the quartile groups. The lack of an association between FV blood flow and inflammatory MRI measures in MS patients, but an association with brain atrophy, suggests that the severity of neurodegenerative process may be related to hemodynamic alterations. MS patients with more advanced global and regional brain atrophy showed low or retrograde FV volume flow.

  16. Blood flow reprograms lymphatic vessels to blood vessels. (United States)

    Chen, Chiu-Yu; Bertozzi, Cara; Zou, Zhiying; Yuan, Lijun; Lee, John S; Lu, MinMin; Stachelek, Stan J; Srinivasan, Sathish; Guo, Lili; Vicente, Andres; Vincente, Andres; Mericko, Patricia; Levy, Robert J; Makinen, Taija; Oliver, Guillermo; Kahn, Mark L


    Human vascular malformations cause disease as a result of changes in blood flow and vascular hemodynamic forces. Although the genetic mutations that underlie the formation of many human vascular malformations are known, the extent to which abnormal blood flow can subsequently influence the vascular genetic program and natural history is not. Loss of the SH2 domain-containing leukocyte protein of 76 kDa (SLP76) resulted in a vascular malformation that directed blood flow through mesenteric lymphatic vessels after birth in mice. Mesenteric vessels in the position of the congenital lymphatic in mature Slp76-null mice lacked lymphatic identity and expressed a marker of blood vessel identity. Genetic lineage tracing demonstrated that this change in vessel identity was the result of lymphatic endothelial cell reprogramming rather than replacement by blood endothelial cells. Exposure of lymphatic vessels to blood in the absence of significant flow did not alter vessel identity in vivo, but lymphatic endothelial cells exposed to similar levels of shear stress ex vivo rapidly lost expression of PROX1, a lymphatic fate-specifying transcription factor. These findings reveal that blood flow can convert lymphatic vessels to blood vessels, demonstrating that hemodynamic forces may reprogram endothelial and vessel identity in cardiovascular diseases associated with abnormal flow.

  17. Bone blood flow and metabolism in humans

    DEFF Research Database (Denmark)

    Heinonen, Ilkka; Kemppainen, Jukka; Kaskinoro, Kimmo


    Human bone blood flow and metabolism during physical exercise remains poorly characterised. In the present study we measured femoral bone blood flow and glucose uptake in young healthy subjects by positron emission tomography in three separate protocols. In six women, blood flow was measured...... in femoral bone at rest and during one leg intermittent isometric exercise with increasing exercise intensities. In nine men, blood flow in femur was determined at rest and during dynamic one leg exercise, and two other physiological perturbations: moderate systemic hypoxia (14 O(2) ) at rest and during...... exercise, and during intra-femoral infusion of high-dose adenosine. Bone glucose uptake was measured at rest and during dynamic one leg exercise in five men. The results indicate that isometric exercise increased femoral bone blood flow from rest (1.8 ± 0.6 ml/100g/min) to low intensity exercise (4.1 ± 1...

  18. Ciliary Blood Flow and Aqueous Humor Production (United States)

    Kiel, J.W.; Hollingsworth, M.; Rao, R.; Chen, M.; Reitsamer, H.A.


    Aqueous humor production is a metabolically active process sustained by the delivery of oxygen and nutrients and removal of metabolic waste by the ciliary circulation. This article describes our investigations into the relationship between ciliary blood flow and aqueous humor production. The results presented indicate that there is a dynamic relationship between ciliary blood flow and aqueous humor production, with production being blood flow independent above a critical level of perfusion, and blood flow dependent below it. The results also show that the plateau portion of the relationship shifts up or down depending on the level of secretory stimulation or inhibition, and that oxygen is one critical factor provided by ciliary blood flow. Also presented is a theoretical model of ocular hydrodynamics incorporating these new findings. PMID:20801226

  19. The Physics of Coronary Blood Flow

    CERN Document Server

    Zamir, M


    Coronary blood flow is blood flow to the heart for its own metabolic needs. In the most common form of heart disease there is a disruption in this flow because of obstructive disease in the vessels that carry the flow. The subject of coronary blood flow is therefore associated mostly with the pathophysiology of this disease, rarely with dynamics or physics. Yet, the system responsible for coronary blood flow, namely the "coronary circulation," is a highly sophisticated dynamical system in which the dynamics and physics of the flow are as important as the integrity of the conducting vessels. While an obstruction in the conducting vessels is a fairly obvious and clearly visible cause of disruption in coronary blood flow, any discord in the complex dynamics of the system can cause an equally grave, though less conspicuous, disruption in the flow. This book is devoted specifically to the dynamics and physics of coronary blood flow. While relevance to the clinical and pathophysiological issues is clearly maintaine...

  20. Blood flow autoregulation in pedicled flaps

    DEFF Research Database (Denmark)

    Bonde, Christian T; Holstein-Rathlou, Niels-Henrik; Elberg, Jens J


    INTRODUCTION: Clinical work on the blood perfusion in skin and muscle flaps has suggested that some degree of blood flow autoregulation exists in such flaps. An autoregulatory mechanism would enable the flap to protect itself from changes in the perfusion pressure. The purpose of the present study...... was to evaluate if, and to what extent, a tissue flap could compensate a reduction in blood flow due to an acute constriction of the feed artery. Further, we wanted to examine the possible role of smooth muscle L-type calcium channels in the autoregulatory mechanism by pharmacological intervention with the L......-type calcium channel blocker nimodipine and the vasodilator papaverine. MATERIAL AND METHODS: Pedicled flaps were raised in pigs. Flow in the pedicle was reduced by constriction of the feed artery (n=34). A transit time flow probe measured the effect on blood flow continuously. Following this, three different...

  1. Measurement of liver volumes by portal vein flow by Doppler ultrasound in living donor liver transplantation. (United States)

    Choi, Sang Hyun; Kwon, Jae Hyun; Kim, Kyoung Won; Jang, Hye Young; Kim, Ji Hye; Kwon, Heon-Ju; Lee, Jeongjin; Song, Gi-Won; Lee, Sung-Gyu


    The accurate estimation of liver volume and right/left ratio in donor candidates is critical, but there is no method using portal vein (PV) flow. Of 125 donor candidates, right/left liver volume ratio was estimated using ultrasound (US)-PV area ratio and Doppler US-PV flow ratio, and the results were compared with CT volumetry. We analyzed these results in 76 donors who underwent hemihepatectomy. We evaluated diagnostic values of Doppler US-PV flow for Doppler US-PV flow with actual graft weight. In 125 donor candidates, 96.8% showed Doppler US-PV flow ratio and CT volumetry. Compared with CT volumetry, the mean percentage difference of liver volume ratio by Doppler US-PV flow ratio was significantly smaller than that by US-PV area ratio (±0.7% vs ±6.3%, PDoppler US-PV flow ratio than that by US-PV area ratio (±1.0% vs ±6.0%, PDoppler US-PV flow was linearly correlated with graft weight (R 2 =0.770, PDoppler US-PV flow can effectively estimate right/left liver volume ratio in initial donor investigation. However, Doppler US-PV flow is not accurate in assessing donors with <30% remnant liver volume and in estimating actual graft weight. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  2. Blood ammonia levels in liver cirrhosis: a clue for the presence of portosystemic collateral veins

    Directory of Open Access Journals (Sweden)

    Tripodi Francesca


    Full Text Available Abstract Background Portal hypertension leads to the formation of portosystemic collateral veins in liver cirrhosis. The resulting shunting is responsible for the development of portosystemic encephalopathy. Although ammonia plays a certain role in determining portosystemic encephalopathy, the venous ammonia level has not been found to correlate with the presence or severity of this entity. So, it has become partially obsolete. Realizing the need for non-invasive markers mirroring the presence of esophageal varices in order to reduce the number of endoscopy screening, we came back to determine whether there was a correlation between blood ammonia concentrations and the detection of portosystemic collateral veins, also evaluating splenomegaly, hypersplenism (thrombocytopenia and the severity of liver cirrhosis. Methods One hundred and fifty three consecutive patients with hepatic cirrhosis of various etiologies were recruited to participate in endoscopic and ultrasonography screening for the presence of portosystemic collaterals mostly esophageal varices, but also portal hypertensive gastropathy and large spontaneous shunts. Results Based on Child-Pugh classification, the median level of blood ammonia was 45 mcM/L in 64 patients belonging to class A, 66 mcM/L in 66 patients of class B and 108 mcM/L in 23 patients of class C respectively (p The grade of esophageal varices was concordant with venous ammonia levels (rho 0.43, p Conclusion Identifying cirrhotic patients with high blood ammonia concentrations could be clinically useful, as high levels would lead to suspicion of being in presence of collaterals, in clinical practice of esophageal varices, and pinpoint those patients requiring closer follow-up and endoscopic screening.

  3. Brachial blood flow under relative levels of blood flow restriction is decreased in a nonlinear fashion. (United States)

    Mouser, J Grant; Ade, Carl J; Black, Christopher D; Bemben, Debra A; Bemben, Michael G


    Blood flow restriction (BFR), the application of external pressure to occlude venous return and restrict arterial inflow, has been shown to increase muscular size and strength when combined with low-load resistance exercise. BFR in the research setting uses a wide range of pressures, applying a pressure based upon an individual's systolic pressure or a percentage of occlusion pressure; not a directly determined reduction in blood flow. The relationship between relative pressure and blood flow has not been established. To measure blood flow in the arm under relative levels of BFR. Forty-five people (18-40 years old) participated. Arterial occlusion pressure in the right arm was measured using a 5-cm pneumatic cuff. Blood flow in the brachial artery was measured at rest and at pressures between 10% and 90% of occlusion using ultrasound. Blood flow decreased in a nonlinear, stepped fashion. Blood flow decreased at 10% of occlusion and remained constant until decreasing again at 40%, where it remained until 90% of occlusion. The decrease in brachial blood flow is not proportional to the applied relative pressure. The prescription of blood flow restriction should take into account the stimulus provided at each relative level of blood flow. © 2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  4. Frequency encoding in renal blood flow regulation

    DEFF Research Database (Denmark)

    Marsh, Donald J; Sosnovtseva, Olga; Pavlov, Alexey N


    With a model of renal blood flow regulation, we examined consequences of tubuloglomerular feedback (TGF) coupling to the myogenic mechanism via voltage-gated Ca channels. The model reproduces the characteristic oscillations of the two mechanisms and predicts frequency and amplitude modulation...... of the myogenic oscillation by TGF. Analysis by wavelet transforms of single-nephron blood flow confirms that both amplitude and frequency of the myogenic oscillation are modulated by TGF. We developed a double-wavelet transform technique to estimate modulation frequency. Median value of the ratio of modulation...... TGF cycle to the next. We used a blood pressure signal recorded by telemetry from a conscious rat as the input to the model. Blood pressure fluctuations induced variability in the modulation records similar to those found in the nephron blood flow results. Frequency and amplitude modulation can...

  5. Effects of respiratory manoeuvres on hepatic vein Doppler waveform and flow velocities in a healthy population

    Energy Technology Data Exchange (ETDEWEB)

    Altinkaya, Naime, E-mail: [Department of Radiology, Baskent University Medical School, Adana (Turkey); Baskent University, Faculty of Medicine, Department of Radiology, Adana (Turkey); Koc, Zafer, E-mail: [Department of Radiology, Baskent University Medical School, Adana (Turkey); Baskent University, Faculty of Medicine, Department of Radiology, Adana (Turkey); Ulusan, Serife, E-mail: [Department of Radiology, Baskent University Medical School, Adana (Turkey); Baskent University, Faculty of Medicine, Department of Radiology, Adana (Turkey); Demir, Senay, E-mail: [Department of Radiology, Baskent University Medical School, Adana (Turkey); Baskent University, Faculty of Medicine, Department of Radiology, Adana (Turkey); Gurel, Kamil, E-mail: [Department of Radiology, Baskent University Medical School, Adana (Turkey); Baskent University, Faculty of Medicine, Department of Radiology, Adana (Turkey)


    Objective: This study was performed to determine the variations in Doppler waveforms and flow velocity during respiratory manoeuvres in healthy individuals with no liver disease. Materials and methods: In total, 100 individuals (75 women and 25 men) without known cardiac or liver disease were examined prospectively with duplex Doppler ultrasonography (US). We recorded the Doppler waveforms and peak systolic velocities (V{sub max}) of the middle hepatic vein during normal respiration, during breath-holding after quiet expiration and also during deep inspiration. Doppler waveforms are categorised as triphasic, biphasic or monophasic. Results: During normal respiration, hepatic venous waveforms were triphasic in 93% of subjects, monophasic in 6% and biphasic in 1%. During breath-holding after quiet expiration, the percentages were 91%, 6% and 3%, respectively. During deep inspiration, they were 80%, 18% and 2%, respectively. Although significant differences were noted between rates during deep inspiration and normal respiration, they were quite similar during normal respiration and breath-holding after quiet expiration (P < 0.05). The values of V{sub max} were significantly higher during normal respiration compared to quiet expiration and during quiet expiration compared to deep inspiration (P < 0.05). Conclusion: The velocities and waveforms of hepatic veins varied during respiratory manoeuvres. The status of respiration must be taken into consideration whilst examining the hepatic vein waveforms and velocities with duplex Doppler US.

  6. Cerebral blood flow response to functional activation

    DEFF Research Database (Denmark)

    Paulson, Olaf B; Hasselbalch, Steen G; Rostrup, Egill


    Cerebral blood flow (CBF) and cerebral metabolic rate are normally coupled, that is an increase in metabolic demand will lead to an increase in flow. However, during functional activation, CBF and glucose metabolism remain coupled as they increase in proportion, whereas oxygen metabolism only...

  7. Neural control of choroidal blood flow. (United States)

    Reiner, Anton; Fitzgerald, Malinda E C; Del Mar, Nobel; Li, Chunyan


    The choroid is richly innervated by parasympathetic, sympathetic and trigeminal sensory nerve fibers that regulate choroidal blood flow in birds and mammals, and presumably other vertebrate classes as well. The parasympathetic innervation has been shown to vasodilate and increase choroidal blood flow, the sympathetic input has been shown to vasoconstrict and decrease choroidal blood flow, and the sensory input has been shown to both convey pain and thermal information centrally and act locally to vasodilate and increase choroidal blood flow. As the choroid lies behind the retina and cannot respond readily to retinal metabolic signals, its innervation is important for adjustments in flow required by either retinal activity, by fluctuations in the systemic blood pressure driving choroidal perfusion, and possibly by retinal temperature. The former two appear to be mediated by the sympathetic and parasympathetic nervous systems, via central circuits responsive to retinal activity and systemic blood pressure, but adjustments for ocular perfusion pressure also appear to be influenced by local autoregulatory myogenic mechanisms. Adaptive choroidal responses to temperature may be mediated by trigeminal sensory fibers. Impairments in the neural control of choroidal blood flow occur with aging, and various ocular or systemic diseases such as glaucoma, age-related macular degeneration (AMD), hypertension, and diabetes, and may contribute to retinal pathology and dysfunction in these conditions, or in the case of AMD be a precondition. The present manuscript reviews findings in birds and mammals that contribute to the above-summarized understanding of the roles of the autonomic and sensory innervation of the choroid in controlling choroidal blood flow, and in the importance of such regulation for maintaining retinal health. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. 21 CFR 870.2120 - Extravascular blood flow probe. (United States)


    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Extravascular blood flow probe. 870.2120 Section... blood flow probe. (a) Identification. An extravascular blood flow probe is an extravascular ultrasonic or electromagnetic probe used in conjunction with a blood flowmeter to measure blood flow in a...

  9. Blood flow distribution in cerebral arteries. (United States)

    Zarrinkoob, Laleh; Ambarki, Khalid; Wåhlin, Anders; Birgander, Richard; Eklund, Anders; Malm, Jan


    High-resolution phase-contrast magnetic resonance imaging can now assess flow in proximal and distal cerebral arteries. The aim of this study was to describe how total cerebral blood flow (tCBF) is distributed into the vascular tree with regard to age, sex and anatomic variations. Forty-nine healthy young (mean 25 years) and 45 elderly (mean 71 years) individuals were included. Blood flow rate (BFR) in 21 intra- and extracerebral arteries was measured. Total cerebral blood flow was defined as BFR in the internal carotid plus vertebral arteries and mean cerebral perfusion as tCBF/brain volume. Carotid/vertebral distribution was 72%/28% and was not related to age, sex, or brain volume. Total cerebral blood flow (717 ± 123 mL/min) was distributed to each side as follows: middle cerebral artery (MCA), 21%; distal MCA, 6%; anterior cerebral artery (ACA), 12%, distal ACA, 4%; ophthalmic artery, 2%; posterior cerebral artery (PCA), 8%; and 20% to basilar artery. Deviating distributions were observed in subjects with 'fetal' PCA. Blood flow rate in cerebral arteries decreased with increasing age (Psystem.

  10. Influence of coronary territory on flow profiles of saphenous vein grafts. (United States)

    Amin, Sanaz; Werner, Raphael S; Madsen, Per Lav; Krasopoulos, George; Taggart, David P


    Differing perfusion of the left and right ventricular coronary territory may influence flow-profiles of saphenous vein grafts (SVGs). We compared flow parameters, measured by transit-time flowmetry (TTFM), in left- and right-sided SVGs during coronary artery by-pass grafting (CABG). Routine TTFM measurements were obtained in 167 SVGs to the left territory (55%) and 134 SVGs to the right territory (total of 301 SVGs in 207 patients). The four standard TTFM parameters, [mean graft flow (MGF), pulsatility index (PI), percentage diastolic filling (%DF), and percentage backward flow (%BF)] were compared. Differences in flow parameters were also examined according to surgical technique (on- vs. off-pump). No significant difference between coronary territories was found for MGF, PI and %BF. However, a higher %DF was noted in left-sided SVGs in the overall cohort as well as in the on-pump (both p territory (1.2 ± 2.5 vs. 2.3 ± 3.0, p = 0.023). In a multivariate regression analysis, anastomosing a SVG to the left territory was weakly associated with higher PI (OR = 0.36, p = 0.026) and strongly associated with higher %DF (OR = 5.1, p < 0.001). No significant association was found for MGF, PI, %DF or %BF in either the on-pump nor the off-pump cohorts. Although statistically significant, the established differences in TTFM parameters between left- and right-sided vein grafts were small and unlikely to be of clinical relevance.

  11. The gingival vein as a minimally traumatic site for multiple blood sampling in guinea pigs and hamsters. (United States)

    Rodrigues, Mariana Valotta; de Castro, Simone Oliveira; de Albuquerque, Cynthia Zaccanini; Mattaraia, Vânia Gomes de Moura; Santoro, Marcelo Larami


    Laboratory animals are still necessary in scientific investigation and vaccine testing, but while novel methodological approaches are not available for their replacement, the search for new, humane, easy, and painless methods is necessary to diminish their stress and pain. When multiple blood samples are to be collected from hamsters and guinea pigs, the number of available venipuncture sites-which are greatly diminished in these species in comparison with other rodents due to the absence of a long tail-, harasses animal caregivers and researchers. Thus, this study aimed to evaluate if gingival vein puncture could be used as an additional route to obtain multiple blood samples from anesthetized hamsters and guinea pigs in such a way that animal behavior, well-being or hematological parameters would not be altered. Thus, twelve anesthetized Syrian golden hamsters and English guinea pigs were randomly allocated in two groups: a control group, whose blood samples were not collected, and an experimental group in which blood samples (200 microliters) were collected by gingival vein puncture at weekly intervals over six weeks. Clinical assessment, body weight gain and complete blood cell count were evaluated weekly, and control and experimental animals were euthanized at week seven, when the mentolabial region was processed to histological analyses. Multiple blood sampling from the gingival vein evoked no clinical manifestations or alteration in the behavioral repertoire, nor a statistically significant difference in weight gain in both species. Guinea pigs showed no alteration in red blood cell, leukocyte or platelet parameters over time. Hamsters developed a characteristic pattern of age-related physiological changes, which were considered normal. Histological analyses showed no difference in morphological structures in the interdental gingiva, confirming that multiple blood sampling is barely traumatic. Thus, these results evidence that blood collection from multiple

  12. Quantifying the influence of oscillatory flow disturbances on blood flow. (United States)

    Gabriel, Sargon A; Ding, Yan; Feng, Yuqing


    Pulsatile blood flow is renowned for inducing localised flow disturbances that are characterised by significant oscillations. These flow disturbances are recognised to have a physiologic significance within the cardiovascular system, particularly with respect to their proatherogenic expression on endothelial cells. Flow disturbances also impart significant influence on the mechanics of cardiovascular flow and are formally shown in the present study to be coupled to the period-average behaviour of a pulsatile flow field, causing it to be misrepresented by its steady-equivalent; which is often used in models of atherogenesis and hence limits their reliability. It is demonstrated that a measure of the localised influence of flow disturbances on the period-average flow can be realised by the relative significance of their kinetic energy, which is quantified by the introduced Oscillatory Kinetic Energy Index (OKEI). A specific measure of direction-reversing oscillations is also developed with the introduction of the Oscillatory Flow Index (OFI), which is an extension of the wall-bound Oscillatory Shear Index (OSI) onto flow and wall spaces. A case study of a human carotid artery is made; wherein pulsatile flow is studied relative to its steady-equivalent state. The introduced indices are demonstrated to collectively identify oscillatory flow disturbances within the flow; quantifying their spatial distribution and influence on the flow field. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Dynamic measurements of total hepatic blood flow with Phase Contrast MRI

    Energy Technology Data Exchange (ETDEWEB)

    Yzet, Thierry [Department of Radiology, University Hospital, Place Victor Pauchet, 80054 Amiens cedex 1 (France)], E-mail:; Bouzerar, Roger [Department of Imaging and Biophysics, University Hospital, Jules Verne University of Picardie, Place Victor Pauchet, 80054 Amiens cedex 1 (France)], E-mail:; Baledent, Olivier [Department of Imaging and Biophysics, University Hospital, Jules Verne University of Picardie, Place Victor Pauchet, 80054 Amiens cedex 1 (France)], E-mail:; Renard, Cedric [Department of Radiology, University Hospital, Place Victor Pauchet, 80054 Amiens cedex 1 (France)], E-mail:; Lumbala, Didier Mbayo [Department of Radiology, University Hospital, Place Victor Pauchet, 80054 Amiens cedex 1 (France)], E-mail:; Nguyen-Khac, Eric [Mobile Unit of Alcoology, University Hospital, Place Victor Pauchet, 80054 Amiens cedex 1 (France)], E-mail:; Regimbeau, Jean-Marc [Department of Visceral and Digestive General Surgery, University Hospital, Place Victor Pauchet, 80054 Amiens cedex 1 (France)], E-mail:; Deramond, H. [Department of Radiology, University Hospital, Place Victor Pauchet, 80054 Amiens cedex 1 (France)], E-mail:; Meyer, Marc-Etienne [Department of Imaging and Biophysics, University Hospital, Jules Verne University of Picardie, Place Victor Pauchet, 80054 Amiens cedex 1 (France)], E-mail:


    Background/Aims: To measure total hepatic blood flow including portal and proper hepatic artery flows as well as the temporal evolution of the vessel's section during a cardiac cycle. Methods: Twenty healthy subjects, with a mean age of 26 years, were explored. Magnetic resonance imaging blood flow measurements were carried out in the portal vein and the proper hepatic artery. MR studies were performed using a 1.5T imager (General Electric Medical Systems). Gradient-echo 2D Fast Cine Phase Contrast sequences were used with both cardiac and respiratory gatings. Data analysis was performed using a semi-automatic software built in our laboratory. Results: The total hepatic flow rate measured was 1.35 {+-} 0.18 L/min or 19.7 {+-} 4.6 mL/(min kg). The proper hepatic artery provided 19.1% of the total hepatic blood flow entering the liver. Those measurements were in agreement with earlier studies using direct measurements. Mean and maximum velocities were also assessed and a discrepancy between our values and the literature's Doppler data was found. Measurements of the portal vein area have shown a mean variation, defined as a 'pulsatility' index of 18% over a cardiac cycle. Conclusions: We report here proper hepatic artery blood flow rate measurements using MRI. Associated with portal flow measurements, we have shown the feasibility of total hepatic flowmetry using a non-invasive and harmless technique.

  14. Importance of blood cultures from peripheral veins in pediatric patients with cancer and a central venous line

    DEFF Research Database (Denmark)

    Handrup, Mette Møller; Møller, Jens Kjølseth; Rutkjaer, Cecilie


    When an infection is suspected in a child with cancer and a central venous line (CVL), cultures are often only obtained from the CVL and not from a peripheral vein (PV). This study was undertaken to evaluate the importance of concomitant blood cultures from the CVL and a PV....

  15. An implantable blood pressure and flow transmitter. (United States)

    Rader, R. D.; Meehan, J. P.; Henriksen, J. K. C.


    A miniature totally implantable FM/FM telemetry system has been developed to simultaneously measure blood pressure and blood flow, thus providing an appreciation of the hemodynamics of the circulation to the entire body or to a particular organ. Developed for work with animal subjects, the telemetry system's transmission time is controlled by an RF signal that permits an operating life of several months. Pressure is detected by a miniature intravascular transducer and flow is detected by an extravascular interferometric ultrasonic technique. Both pressure and flow are calibrated prior to implanting. The pressure calibration can be checked after the implanting by cannulation; flow calibration can be verified only at the end of the experiment by determining the voltage output from the implanted sensing system as a function of several measured flow rates. The utility of this device has been established by its use in investigating canine renal circulation during exercise, emotional encounters, administration of drugs, and application of accelerative forces.

  16. Influence of blood flow on shear stress responsive genes in the development of cardiac malformations : the involvement of the endothelin-1 pathway

    NARCIS (Netherlands)

    Groenendijk, Bianca C.W.


    Ligation of the right lateral vitelline vein in chicken embryos (venous clip) results in changes in the intracardial blood flow patterns, and in functional and morphological cardiovascular defects. This demonstrates that blood flow, of which shear stress is a derivative, plays an important role in

  17. Meal-induced changes in splanchnic blood flow and oxygen uptake in middle-aged healthy humans

    DEFF Research Database (Denmark)

    Madsen, Jan L; Søndergaard, Susanne B; Møller, Søren


    healthy men (52-76 years). Splanchnic blood flow was measured during hepatic vein catheterization by indirect Fick principle with indocyanine green as the indicator. Splanchnic oxygen uptake was calculated from splanchnic blood flow and the arteriovenous oxygen difference. RESULTS: The meal induced...... in middle-aged healthy humans. Our data may be relevant for the evaluation of corresponding data from patients with suspected chronic intestinal ischaemia....

  18. Whole blood rotation thromboelastometry (ROTEM®) profiles in subjects with non-neoplastic portal vein thrombosis. (United States)

    Rossetto, Valeria; Spiezia, Luca; Senzolo, Marco; Rodriguez-Castro, Kryssia I; Maggiolo, Sara; Simioni, Paolo


    The coagulation pattern and the determinants of portal vein thrombosis (PVT), both in patients with and without cirrhosis, are still largely unknown. The aim of this study was to evaluate whole blood thromboelastometry profile, performed by ROTEM®, of both cirrhotic and non-cirrhotic subjects with PVT. Two different groups were considered: i) 14 non-cirrhotic PVT patients, ii) 35 cirrhotic patients with PVT. Controls were sex- and age-matched healthy volunteers and cirrhotic subjects without PVT, respectively. ROTEM® assays (i.e. INTEM, EXTEM, NATEM, and FIBTEM) and traditional coagulative parameters (i.e. platelet count, PT/INR, aPTT, and fibrinogen) were performed on blood samples from each subject. There were no significant differences in ROTEM® profile, as for INTEM, EXTEM, and NATEM assays, and in traditional coagulative parameters, between PVT patients, both with and without cirrhosis, and control groups. Interestingly, Maximum Clot Firmness (MCF) in FIBTEM was significantly higher in non-cirrhotic PVT patients (19 mm) than in healthy volunteers (11 mm, p<0.05). The amplitude of MCF in FIBTEM revealed to be a useful tool to discriminate non-cirrhotic subjects with PVT from those without thrombotic events. Larger prospective studies are needed to evaluate the relevance of the association between the alterations of ROTEM® profiles and PVT in cirrhotic patients. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Penile blood flow by xenon-133 washout

    Energy Technology Data Exchange (ETDEWEB)

    Haden, H.T.; Katz, P.G.; Mulligan, T.; Zasler, N.D.


    Penile erectile failure is often attributed to abnormalities of vascular supply or drainage, but few direct measurements of penile blood flow have been made. We describe the xenon washout method for measurement of penile blood flow, and present the results obtained in a group of normal and impotent subjects. The procedure was performed with standard nuclear imaging equipment. Flaccid-state penile blood flow in the impotent patients studied was not significantly different from the normal group, suggesting that flaccid-state measurements may not be helpful in evaluation of erectile failure. However, this method can be used to measure penile venous outflow with stimulated or induced erection, and may provide a method for detecting abnormal venous leakage.

  20. Huge Varicose Inferior Mesenteric Vein: an Unanticipated {sup 99m}Tc-labeled Red Blood Cell Scintigraphy Finding

    Energy Technology Data Exchange (ETDEWEB)

    Hoseinzadeh, Samaneh; Shafiei, Babak; Salehian, Mohamadtaghi; Neshandar Asli, Isa; Ghodoosi, Iraj [Shaheed Beheshti Medical University, Tehran (Iran, Islamic Republic of)


    Ectopic varices (EcV) are enlarged portosystemic venous collaterals, which usually develop secondary to portal hypertension (PHT). Mesocaval collateral vessels are unusual pathways to decompress the portal system. Here we report the case of a huge varicose inferior mesenteric vein (IMV) that drained into peri rectal collateral veins, demonstrated by {sup 99m}Tc-labeled red blood cell (RBC) scintigraphy performed for lower gastrointestinal (GI) bleeding in a 14-year-old girl. This case illustrates the crucial role of {sup 99m}Tc-labeled RBC scintigraphy for the diagnosis of rare ectopic lower GI varices.

  1. Regulation of blood flow by prostaglandins

    DEFF Research Database (Denmark)

    Boushel, Robert Christopher; Langberg, H; Risum, N


    Prostaglandins (PGs) belong to the family of prostanoids together with thromboxanes and are produced mainly from arachadonic acid by the enzyme cyclooxygenase. PGs are known to stimulate platelet aggregation, mediate inflammation and edema, play a role in bone metabolism and in biological...... adaptation of connective tissues e.g. tendon. This review covers the role of PG for mediating tissue blood flow at rest and during increases in metabolic demand such as exercise and reactive hyperaemia. There is strong evidence that PGs contribute to elevate blood flow at rest and during reactive hyperaemia...

  2. Arterial secondary blood flow patterns visualized with vector flow ultrasound

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Hansen, Jens Munk


    and velocity magnitudes the blood flow patterns were visualised with streamlines in Matlab (Mathworks, Natick, MA, USA). The rotational flow was quantified by the angular frequency for each cardiac cycle, and the mean rotational frequencies and standard deviations were calculated for the abdominal aorta f-1......This study presents the first quantification and visualisation of secondary flow patterns with vector flow ultrasound. The first commercial implementation of the vector flow method Transverse Oscillation was used to obtain in-vivo, 2D vector fields in real-time. The hypothesis of this study...... was that the rotational direction is constant within each artery. Three data sets of 10 seconds were obtained from three main arteries in healthy volunteers. For each data set the rotational flow patterns were identified during the diastole. Each data set contains a 2D vector field over time and with the vector angles...

  3. Using flow feature to extract pulsatile blood flow from 4D flow MRI images (United States)

    Wang, Zhiqiang; Zhao, Ye; Yu, Whitney; Chen, Xi; Lin, Chen; Kralik, Stephen F.; Hutchins, Gary D.


    4D flow MRI images make it possible to measure pulsatile blood flow inside deforming vessel, which is critical in accurate blood flow visualization, simulation, and evaluation. Such data has great potential to overcome problems in existing work, which usually does not reflect the dynamic nature of elastic vessels and blood flows in cardiac cycles. However, the 4D flow MRI data is often low-resolution and with strong noise. Due to these challenges, few efforts have been successfully conducted to extract dynamic blood flow fields and deforming artery over cardiac cycles, especially for small artery like carotid. In this paper, a robust flow feature, particularly the mean flow intensity is used to segment blood flow regions inside vessels from 4D flow MRI images in whole cardiac cycle. To estimate this flow feature more accurately, adaptive weights are added to the raw velocity vectors based on the noise strength of MRI imaging. Then, based on this feature, target arteries are tracked in at different time steps in a cardiac cycle. This method is applied to the clinical 4D flow MRI data in neck area. Dynamic vessel walls and blood flows are effectively generated in a cardiac cycle in the relatively small carotid arteries. Good image segmentation results on 2D slices are presented, together with the visualization of 3D arteries and blood flows. Evaluation of the method was performed by clinical doctors and by checking flow volume rates in the vertebral and carotid arteries.

  4. Changes in intracranial venous blood flow and pulsatility in Alzheimer's disease: A 4D flow MRI study. (United States)

    Rivera-Rivera, Leonardo A; Schubert, Tilman; Turski, Patrick; Johnson, Kevin M; Berman, Sara E; Rowley, Howard A; Carlsson, Cynthia M; Johnson, Sterling C; Wieben, Oliver


    Cerebral blood flow, arterial pulsation, and vasomotion may be important indicators of cerebrovascular health in aging and diseases of aging such as Alzheimer's disease. Noninvasive markers that assess these characteristics may be helpful in the study of co-occurrence of these diseases and potential additive and interacting effects. In this study, 4D flow MRI was used to measure intra-cranial flow features with cardiac-gated phase contrast MRI in cranial arteries and veins. Mean blood flow and pulsatility index as well as the transit time of the peak flow from the middle cerebral artery to the superior sagittal sinus were measured in a total of 104 subjects comprising of four groups: (a) subjects with Alzheimer's disease, (b) age-matched controls, (c) subjects with mild cognitive impairment, and (d) a group of late middle-aged with parental history of sporadic Alzheimer's disease. The Alzheimer's disease group exhibited: a significant decrease in mean blood flow in the superior sagittal sinus, transverse sinus, middle cerebral artery, and internal carotid arteries; a significant decrease of the peak and end diastolic blood flow in the middle cerebral artery and superior sagittal sinus; a faster transmission of peak flow from the middle cerebral artery to the superior sagittal sinus and increased pulsatility index along the carotid siphon.

  5. Nonlinear interactions in renal blood flow regulation

    DEFF Research Database (Denmark)

    Marsh, Donald J.; Sosnovtseva, Olga; Chon, Ki H.


    resistance and glomerular capillary pressure. The model couples TGF input to voltage-gated Ca channels. It predicts autoregulation of GFR and renal blood flow, matches experimental measures of tubular pressure and macula densa NaCl concentration, and predicts TGF-induced oscillations and a faster smaller...

  6. Frequency encoding in renal blood flow regulation

    DEFF Research Database (Denmark)

    Marsh, D.J.; Sosnovtseva, Olga; Pavlov, A.N.


    With a model of renal blood flow regulation, we examined consequences of tubuloglomerular feedback (TGF) coupling to the myogenic mechanism via voltage-gated Ca channels. The model reproduces the characteristic oscillations of the two mechanisms and predicts frequency and amplitude modulation...

  7. Cerebral blood flow in acute mountain sickness

    DEFF Research Database (Denmark)

    Jensen, J B; Wright, Anne; Lassen, N A


    Changes in cerebral blood flow (CBF) were measured using the radioactive xenon technique and were related to the development of acute mountain sickness (AMS). In 12 subjects, ascending from 150 to 3,475 m, CBF was 24% increased at 24 h [45.1 to 55.9 initial slope index (ISI) units] and 4% increased...

  8. Blood flow dynamics in the snake spectacle. (United States)

    van Doorn, Kevin; Sivak, Jacob G


    The eyes of snakes are shielded beneath a layer of transparent integument referred to as the 'reptilian spectacle'. Well adapted to vision by virtue of its optical transparency, it nevertheless retains one characteristic of the integument that would otherwise prove detrimental to vision: its vascularity. Given the potential consequence of spectacle blood vessels on visual clarity, one might expect adaptations to have evolved that mitigate their negative impact. Earlier research demonstrated an adaptation to their spatial layout in only one species to reduce the vessels' density in the region serving the foveal and binocular visual fields. Here, we present a study of spectacle blood flow dynamics and provide evidence of a mechanism to mitigate the spectacle blood vessels' deleterious effect on vision by regulation of blood flow through them. It was found that when snakes are at rest and undisturbed, spectacle vessels undergo cycles of dilation and constriction, such that the majority of the time the vessels are fully constricted, effectively removing them from the visual field. When snakes are presented with a visual threat, spectacle vessels constrict and remain constricted for longer periods than occur during the resting cycles, thus guaranteeing the best possible visual capabilities in times of need. Finally, during the snakes' renewal phase when they are generating a new stratum corneum, the resting cycle is abolished, spectacle vessels remain dilated and blood flow remains strong and continuous. The significance of these findings in terms of the visual capabilities and physiology of snakes is discussed.

  9. Physiological and Pathological Impact of Blood Sampling by Retro-Bulbar Sinus Puncture and Facial Vein Phlebotomy in Laboratory Mice

    DEFF Research Database (Denmark)

    Teilmann, Anne Charlotte; Nygaard Madsen, Andreas; Holst, Birgitte


    time points, and the samples were analyzed for plasma corticosterone. Body weights were measured at the day of blood sampling and the day after blood sampling, and the food consumption was recorded automatically during the 24 hours post-procedure. At the end of study, cheeks and orbital regions were...... weight following blood sampling, but the body weight loss was higher in mice subjected to facial vein phlebotomy. The food consumption was not significantly different between the two groups. At gross necropsy, subcutaneous hematomas were found in both groups and the histopathological analyses revealed...

  10. Influence of Blood Viscosity on Blood Flow and the Effect of Low Molecular Weight Dextran (United States)

    Dormandy, John A.


    Changes in whole blood viscosity are related to changes in the leg blood flow during infusions of low-molecular-weight dextran and Hartmann's solution. A close inverse correlation exists between changes in viscosity and blood flow, the change in blood flow being about three times greater than the change in blood viscosity. The dextran and Hartmann's solution had a similar effect on blood viscosity and blood flow if corrections are made for the difference in haemodilution. PMID:5129616

  11. Technical note: Measurement of mammary plasma flow in sows by downstream dilution of mammary vein infused para-aminohippuric acid

    DEFF Research Database (Denmark)

    Larsen, Uffe Krogh; Storm, Adam Christian; Theil, Peter Kappel


    catheter was surgically implanted in the femoral artery, and another 2 were inserted in the right cranial mammary vein of 8 second- and third-parity sows on d 76 ± 2 SEM of gestation. On the 3rd and 17th days in milk, arterial and venous blood samples were drawn in hourly intervals from 0.5 h before until...

  12. Changes in chorioretinal blood flow velocity and cerebral blood flow after carotid endarterectomy. (United States)

    Enaida, Hiroshi; Nagata, Shinji; Takeda, Atsunobu; Nakao, Shintaro; Ikeda, Yasuhiro; Ishibashi, Tatsuro


    To investigate the changes in chorioretinal blood flow velocity and cerebral blood after carotid endarterectomy (CEA). Nine patients with moderate to severe internal carotid artery stenosis underwent CEA. Chorioretinal blood flow velocity was measured by laser speckle flowgraphy (LSFG), while cerebral blood flow (CBF) was measured by single-photon emission computed tomography (SPECT), on the affected side both before and after CEA. LSFG was evaluated in five areas to determine mean blur rate, while CBF was calculated from regional CBF and cerebrovascular reactivity (CVR), at the middle cerebral artery (MCA) region of each patient. Five cases showed an increase (mean 3.49 %, range -29.82 to 35.59 %) of average chorioretinal blood flow velocity using LSFG after CEA. A particularly averaged increase in chorioretinal blood flow was observed in the macular area compared with other areas. Similarly, there was an increase in CBF at rest (mean 11.46 %, range -14.51 to 74.14 %) observed using SPECT after surgery. Improvement of CVR was confirmed in four cases. All general and visual symptoms disappeared after CEA. Severe adverse effects, including hyperperfusion syndrome, were not observed in any cases. LSFG may be useful for the analysis of chorioretinal blood flow changes after CEA.

  13. 4D flow MRI assessment of right atrial flow patterns in the normal heart - influence of caval vein arrangement and implications for the patent foramen ovale.

    Directory of Open Access Journals (Sweden)

    Jehill D Parikh

    Full Text Available To investigate atrial flow patterns in the normal adult heart, to explore whether caval vein arrangement and patency of the foramen ovale (PFO may be associated with flow pattern.Time-resolved, three-dimensional velocity encoded magnetic resonance imaging (4D flow was employed to assess atrial flow patterns in thirteen healthy subjects (6 male, 40 years, range 25-50 and thirteen subjects (6 male, 40 years, range 21-50 with cryptogenic stroke and patent foramen ovale (CS-PFO. Right atrial flow was defined as vortical, helico-vortical, helical and multiple vortices. Time-averaged and peak systolic and diastolic flows in the caval and pulmonary veins and their anatomical arrangement were compared.A spectrum of right atrial flow was observed across the four defined categories. The right atrial flow patterns were strongly associated with the relative position of the caval veins. Right atrial flow patterns other than vortical were more common (p = 0.015 and the separation between the superior and inferior vena cava greater (10±5mm versus 3±3mm, p = 0.002 in the CS-PFO group. In the left atrium all subjects except one had counter-clockwise vortical flow. Vortex size varied and was associated with left lower pulmonary vein flow (systolic r = 0.61, p = 0.001, diastolic r = 0.63 p = 0.002. A diastolic vortex was less common and time-averaged left atrial velocity was greater in the CS-PFO group (17±2cm/sec versus 15±1, p = 0.048. One CS-PFO subject demonstrated vortical retrograde flow in the descending aortic arch; all other subjects had laminar descending aortic flow.Right atrial flow patterns in the normal heart are heterogeneous and are associated with the relative position of the caval veins. Patterns, other than 'typical' vortical flow, are more prevalent in the right atrium of those with cryptogenic stroke in the context of PFO. Left atrial flow patterns are more homogenous in normal hearts and show a relationship with flow arising from the left

  14. Preventing Blood Clots After Orthopaedic Surgery

    Medline Plus

    Full Text Available ... in the thigh or calf. Deep vein thrombosis can develop after any major surgery. People who have ... the veins. If it reaches the lungs, it can block the flow of blood to the lungs ...

  15. Preventing Blood Clots After Orthopaedic Surgery

    Medline Plus

    Full Text Available ... of a blood clot within a deep vein. It commonly occurs in the thigh or calf. Deep ... breaks free and travels through the veins. If it reaches the lungs, it can block the flow ...

  16. Cerebral blood flow tomography with xenon-133

    DEFF Research Database (Denmark)

    Lassen, N A


    Cerebral blood flow (CBF) can be measured tomographically by inhalation of Xenon-133. The calculation is based on taking a sequence of tomograms during the wash-in and wash-out phase of the tracer. Due to the dynamic nature of the process, a highly sensitive and fast moving single photon emission...... of other tracers for CBF tomography using SPECT is summarized with emphasis on the 99mTc chelates that freely pass the intact blood-brain barrier. The highly sensitive brain-dedicated SPECT systems described are a prerequisite for achieving high resolution tomograms with such tracers....

  17. Glial and neuronal control of brain blood flow

    DEFF Research Database (Denmark)

    Attwell, David; Buchan, Alastair M; Charpak, Serge


    Blood flow in the brain is regulated by neurons and astrocytes. Knowledge of how these cells control blood flow is crucial for understanding how neural computation is powered, for interpreting functional imaging scans of brains, and for developing treatments for neurological disorders. It is now...... recognized that neurotransmitter-mediated signalling has a key role in regulating cerebral blood flow, that much of this control is mediated by astrocytes, that oxygen modulates blood flow regulation, and that blood flow may be controlled by capillaries as well as by arterioles. These conceptual shifts...... in our understanding of cerebral blood flow control have important implications for the development of new therapeutic approaches....

  18. Cine phase-contrast MR to assess portal blood flow in a 10-year-old girl with abdominal aortic coarctation: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Clark, T.W.I.; Culham, J.A.G. [Department of Radiology, British Columbia Children`s Hospital, Vancouver, BC (Canada)


    We report the case of a 10-year-old girl with repaired abdominal aortic coarctation in whom chronic mesenteric ischemia was clinically suspected. Cine phase-contrast magnetic resonance (MR) was used to determine the difference between fasting and postprandial portal blood flow. Fasting flow rates in the portal vein were normal. After a meal, blood flow in the portal vein increased 226 % over the fasting state, showing normal augmentation. To the best of our knowledge, this is the first application of this technique to a pediatric setting. (orig.) With 2 figs., 10 refs.

  19. Red blood cell in simple shear flow (United States)

    Chien, Wei; Hew, Yayu; Chen, Yeng-Long


    The dynamics of red blood cells (RBC) in blood flow is critical for oxygen transport, and it also influences inflammation (white blood cells), thrombosis (platelets), and circulatory tumor migration. The physical properties of a RBC can be captured by modeling RBC as lipid membrane linked to a cytoskeletal spectrin network that encapsulates cytoplasm rich in hemoglobin, with bi-concave equilibrium shape. Depending on the shear force, RBC elasticity, membrane viscosity, and cytoplasm viscosity, RBC can undergo tumbling, tank-treading, or oscillatory motion. We investigate the dynamic state diagram of RBC in shear and pressure-driven flow using a combined immersed boundary-lattice Boltzmann method with a multi-scale RBC model that accurately captures the experimentally established RBC force-deformation relation. It is found that the tumbling (TU) to tank-treading (TT) transition occurs as shear rate increases for cytoplasm/outer fluid viscosity ratio smaller than 0.67. The TU frequency is found to be half of the TT frequency, in agreement with experiment observations. Larger viscosity ratios lead to the disappearance of stable TT phase and unstable complex dynamics, including the oscillation of the symmetry axis of the bi-concave shape perpendicular to the flow direction. The dependence on RBC bending rigidity, shear modulus, the order of membrane spectrin network and fluid field in the unstable region will also be discussed.

  20. Portal vein thrombosis after reconstruction in 270 consecutive patients with portal vein resections in hepatopancreatobiliary (HPB) surgery. (United States)

    Miyazaki, Masaru; Shimizu, Hiroaki; Ohtuka, Masayuki; Kato, Atsushi; Yoshitomi, Hiroyuki; Furukawa, Katsunori; Takayashiki, Tsukasa; Kuboki, Satoshi; Takano, Shigetsugu; Suzuki, Daisuke; Higashihara, Taku


    This study was aimed to evaluate the occurrence of portal vein thrombosis after portal vein reconstruction. The portal veins were repaired with venorrhaphy, end-to-end, patch graft, and segmental graft in consecutive 270 patients undergoing hepato-pancreto-biliary (HPB) surgery. Portal vein thrombosis was encountered in 20 of 163 of end-to-end, 2 of 56 of venorrhaphy, and 2 of 5 of patch graft groups, as compared with 0 of 46 of segmental graft group (p Portal vein thrombosis occurred more frequently after hepatectomy than after pancreatectomy (p portal vein blood flow was more sufficiently achieved in the early re-operation within 3 days after surgery than in the late re-operation over 5 days after surgery (p portal vein reconstruction. The revision surgery for portal vein thrombosis should be performed within 3 days after surgery. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Accurate Blood Flow Measurements : Are Artificial Tracers Necessary?

    NARCIS (Netherlands)

    Poelma, C.; Kloosterman, A.; Hierck, B.P.; Westerweel, J.


    Imaging-based blood flow measurement techniques, such as particle image velocimetry, have become an important tool in cardiovascular research. They provide quantitative information about blood flow, which benefits applications ranging from developmental biology to tumor perfusion studies. Studies

  2. Modified Numerical Simulation Model of Blood Flow in Bend. (United States)

    Liu, X; Zhou, X; Hao, X; Sang, X


    The numerical simulation model of blood flow in bend is studied in this paper. The curvature modification is conducted for the blood flow model in bend to obtain the modified blood flow model in bend. The modified model is verified by U tube. By comparing the simulation results with the experimental results obtained by measuring the flow data in U tube, it was found that the modified blood flow model in bend can effectively improve the prediction accuracy of blood flow data affected by the curvature effect.

  3. Regional cerebral blood flow in childhood headache

    Energy Technology Data Exchange (ETDEWEB)

    Roach, E.S.; Stump, D.A.


    Regional cerebral blood flow (rCBF) was measured in 16 cranial regions in 23 children and adolescents with frequent headaches using the non-invasive Xenon-133 inhalation technique. Blood flow response to 5% carbon dioxide (CO2) was also determined in 21 patients, while response to 50% oxygen was measured in the two patients with hemoglobinopathy. Included were 10 patients with a clinical diagnosis of migraine, 4 with musculoskeletal headaches, and 3 with features of both types. Also studied were 2 patients with primary thrombocythemia, 2 patients with hemoglobinopathy and headaches, 1 patient with polycythemia, and 1 with headaches following trauma. With two exceptions, rCBF determinations were done during an asymptomatic period. Baseline rCBF values tended to be higher in these young patients than in young adults done in our laboratory. Localized reduction in the expected blood flow surge after CO2 inhalation, most often noted posteriorly, was seen in 8 of the 13 vascular headaches, but in none of the musculoskeletal headache group. Both patients with primary thrombocythemia had normal baseline flow values and altered responsiveness to CO2 similar to that seen in migraineurs; thus, the frequently reported headache and transient neurologic signs with primary thrombocythemia are probably not due to microvascular obstruction as previously suggested. These data support the concept of pediatric migraine as a disorder of vasomotor function and also add to our knowledge of normal rCBF values in younger patients. Demonstration of altered vasomotor reactivity to CO2 could prove helpful in children whose headache is atypical.

  4. Regulation of coronary blood flow during exercise. (United States)

    Duncker, Dirk J; Bache, Robert J


    Exercise is the most important physiological stimulus for increased myocardial oxygen demand. The requirement of exercising muscle for increased blood flow necessitates an increase in cardiac output that results in increases in the three main determinants of myocardial oxygen demand: heart rate, myocardial contractility, and ventricular work. The approximately sixfold increase in oxygen demands of the left ventricle during heavy exercise is met principally by augmenting coronary blood flow (~5-fold), as hemoglobin concentration and oxygen extraction (which is already 70-80% at rest) increase only modestly in most species. In contrast, in the right ventricle, oxygen extraction is lower at rest and increases substantially during exercise, similar to skeletal muscle, suggesting fundamental differences in blood flow regulation between these two cardiac chambers. The increase in heart rate also increases the relative time spent in systole, thereby increasing the net extravascular compressive forces acting on the microvasculature within the wall of the left ventricle, in particular in its subendocardial layers. Hence, appropriate adjustment of coronary vascular resistance is critical for the cardiac response to exercise. Coronary resistance vessel tone results from the culmination of myriad vasodilator and vasoconstrictors influences, including neurohormones and endothelial and myocardial factors. Unraveling of the integrative mechanisms controlling coronary vasodilation in response to exercise has been difficult, in part due to the redundancies in coronary vasomotor control and differences between animal species. Exercise training is associated with adaptations in the coronary microvasculature including increased arteriolar densities and/or diameters, which provide a morphometric basis for the observed increase in peak coronary blood flow rates in exercise-trained animals. In larger animals trained by treadmill exercise, the formation of new capillaries maintains

  5. Genetics Home Reference: alveolar capillary dysplasia with misalignment of pulmonary veins (United States)

    ... misalignment of pulmonary veins Printable PDF Open All Close All Enable Javascript to view the expand/collapse boxes. ... changes restrict normal blood flow, which causes high blood pressure in the pulmonary arteries (pulmonary hypertension) and requires ...

  6. Massage impairs postexercise muscle blood flow and "lactic acid" removal. (United States)

    Wiltshire, E Victoria; Poitras, Veronica; Pak, Melissa; Hong, Terence; Rayner, Jay; Tschakovsky, Michael E


    This study tested the hypothesis that one of the ways sports massage aids muscle recovery from exercise is by increasing muscle blood flow to improve "lactic acid" removal. Twelve subjects performed 2 min of strenuous isometric handgrip (IHG) exercise at 40% maximum voluntary contraction to elevate forearm muscle lactic acid. Forearm blood flow (FBF; Doppler and Echo ultrasound of the brachial artery) and deep venous forearm blood lactate and H+ concentration ([La-], [H+]) were measured every minute for 10 min post-IHG under three conditions: passive (passive rest), active (rhythmic exercise at 10% maximum voluntary contraction), and massage (effleurage and pétrissage). Arterialized [La-] and [H+] from a superficial heated hand vein was measured at baseline. Data are presented as mean +/- SE. Venoarterial [La-] difference ([La-]v-a) at 30 s of post-IHG was the same across conditions (passive = 6.1 +/- 0.6 mmol x L(-1), active = 5.7 +/- 0.6 mmol x L(-1), massage = 5.5 +/- 0.6 mmol x L(-1), NS), whereas FBF was greater in passive (766 +/- 101 mL x min(-1)) versus active (614 +/- 62 mL x min(-1), P = 0.003) versus massage (540 +/- 60 mL x min(-1), P < 0.0001). Total FBF area under the curve (AUC) for 10 min after handgrip was significantly higher in passive versus massage (4203 +/- 531 vs 3178 +/- 304 mL, P = 0.024) but not versus active (3584 +/- 284 mL, P = 0.217). La(-)- efflux (FBF x [La-]v-a) AUC mirrored FBF AUC (passive = 20.5 +/- 2.8 mmol vs massage = 14.7 +/- 1.6 mmol, P = 0.03, vs active = 15.4 +/- 1.9 mmol, P = 0.064). H+ efflux (FBF x [H+]v-a) was greater in passive versus massage at 30 s (2.2 +/- 0.4e(-5) vs 1.3 +/- 0.2e(-5) mmol, P < 0.001) and 1.5 min (1.0 +/- 0.2e(-5) vs 0.6 +/- 0.09e(-5) mmol, P = 0.003) after IHG. Massage impairs La(-) and H+ removal from muscle after strenuous exercise by mechanically impeding blood flow.

  7. Estimation of hepatic blood flow by hydrogen gas clearance

    NARCIS (Netherlands)

    Gouma, D. J.; Coelho, J. C.; Schlegel, J.; Fisher, J. D.; Li, Y. F.; Moody, F. G.


    The hydrogen gas clearance technique was evaluated to estimate regional hepatic blood flow. Initially, the H2 gas method was compared to the indocyanine green clearance in mini pigs. The blood flow measured by the H2 gas method (0.49 +/- 0.03 ml/min/gm) was only 39% of the calculated blood flow by

  8. Decorrelation-based blood flow velocity estimation: effect of spread of flow velocity, linear flow velocity gradients, and parabolic flow.

    NARCIS (Netherlands)

    Lupotti, F.A.; Steen, A.F.W. van der; Mastik, F.; Korte, C.L. de


    In recent years, a new method to measure transverse blood flow, based on the decorrelation of the radio frequency (RF) signals has been developed. In this paper, we investigated the influence of nonuniform flow on the velocity estimation. The decorrelation characteristics of transverse blood flow

  9. Skin blood flow changes during apneic spells in preterm infants

    NARCIS (Netherlands)

    Suichies, H.E.; Aarnoudse, J.G.; Okken, A.; Jentink, H.W.; de Mul, F.F.M.; Greve, Jan


    Changes in skin blood flow during apneic spells were determined in 18 preterm infants using a diode laser Doppler flow meter without light conducting fibres. Heart rate, nasal air flow, impedance pneumography, skin and incubator temperature and laser Doppler skin blood flow were recorded

  10. Blood flow in healed and inflamed periodontal tissues of dogs

    Energy Technology Data Exchange (ETDEWEB)

    Hock, J.M.; Kim, S.


    The objectives of this study were to determine if increased blood flow associated with gingivitis would decrease following resolution of gingival inflammation in dogs with periodontitis; if increased blood flow in inflamed gingiva was associated with changes in the blood flow of alveolar bone, and if blood flow in gingiva and alveolar bone increased if periodontitis was reactivated by ligating teeth. Regional blood flow was measured in dogs with pre-existing periodontitis, using radioisotope-labelled, plastic microspheres. In the first experiment on 4 adult Beagle dogs, teeth in the left jaws were treated to resolve the periodontitis, while teeth in the right jaws were not treated. Gingival and bone blood flow were measured after 12 wk. Blood flow was significantly (p<0.05) lower in non-inflamed healed gingiva (32.1 +- 2.7 ml/min/100 g) than in inflamed gingiva (46.1 +- 5.3 ml/min/100 g). No differences in the blood flow of the alveolar bone underlying inflamed or non-inflamed gingiva were present. In the second experiment, the right mandibular teeth of 5 dogs were treated to resolve periodontitis while teeth in the other quadrants were ligated for 4, 10 or 12 wk. The duration of ligation did not alter blood flow. Gingival blood flow around ligated maxillary and mandibular teeth was comparable and approximately 54% higher than around non-ligated teeth (p<0.03). The difference in blood flow between gingiva with G.I.>1 and gingiva with G.I.<2 was significant (p<0.04). Blood flow in bone was not altered by changes in the inflammatory status of the overlying gingiva. The findings suggest that changes in blood flow associated with inflammation are reversible and that blood flow alveolar bone is regulated independently of gingival blood flow.

  11. Topical menthol increases cutaneous blood flow. (United States)

    Craighead, Daniel H; Alexander, Lacy M


    Menthol, the active ingredient in several topically applied analgesics, activates transient receptor potential melastatin 8 (TRPM8) receptors on sensory nerves and on the vasculature inducing a cooling sensation on the skin. Ilex paraguariensis is also a common ingredient in topical analgesics that has potential vasoactive properties and may alter the mechanisms of action of menthol. We sought to characterize the microvascular effects of topical menthol and ilex application and to determine the mechanism(s) through which these compounds may independently and combined alter cutaneous blood flow. We hypothesized that menthol would induce vasoconstriction and that ilex would not alter skin blood flow (SkBF). Three separate protocols were conducted to examine menthol and ilex-mediated changes in SkBF. In protocol 1, placebo, 4% menthol, 0.7% ilex, and combination menthol+ilex gels were applied separately to the skin and red cell flux was continuously measured utilizing laser speckle contrast imaging (LSCI). In protocol 2, seven concentrations of menthol gel (0.04%, 0.4%, 1%, 2%, 4%, 7%, 8%) were applied to the skin to model the dose-response curve. In protocol 3, placebo, menthol, ilex, and menthol+ilex gels were applied to skin under local thermal control (34°C) both with and without sensory nerve blockage (topical lidocaine 4%). Post-occlusive reactive hyperemia (PORH) and local heating (42°C) protocols were conducted to determine the relative contribution of endothelium derived hyperpolarizing factors (EDHFs)/sensory nerves and nitric oxide (NO), respectively. Red cell flux was normalized to mean arterial pressure expressed as cutaneous vascular conductance (CVC: flux·mmHg(-1)) in all protocols. Topical menthol application increased SkBF compared to placebo (3.41±0.33 vs 1.1±0.19CVC: pmenthol (main effect, pmenthol application during PORH (3.62±0.29 vs. 2.50±0.21flux·mmHg(-1); pmenthol-mediated vasodilation at thermoneutral baseline (1.29±0.19flux·mmHg(-1

  12. Gender dimorphism in differential peripheral blood leukocyte counts in mice using cardiac, tail, foot, and saphenous vein puncture methods

    Directory of Open Access Journals (Sweden)

    Crockett Elahé T


    Full Text Available Abstract Background In many animal models that investigate the pathology of various diseases, there is a need to monitor leukocyte counts and differentials. However, various researchers use a range of different techniques in male and female laboratory animals to collect such blood variable information. These studies are then compared to one another without consideration of the possibility that different bleeding sites or techniques as well as gender may produce varying results. In light of this, the peripheral blood leukocyte counts and differentials of C57BL/6 male and female mice were determined using four blood-sampling techniques: cardiac, tail, foot, and saphenous vein punctures. Methods Blood smears were prepared and stained with Wright-stain for differential cell analysis. The total number of peripheral blood leukocytes was determined with the aid of a hemocytometer. Applying ANOVA and Student t-test analysis made comparisons between groups. Results The total leukocyte counts obtained using the cardiac puncture method were significantly lower as compared to the other three blood sources; saphenous, tail and foot. There were no significant differences between leukocyte counts of blood samples collected from the tail, saphenous, and foot. Additionally, no significant differences were observed in total leukocyte counts between male and female mice. Differential analysis showed lymphocytes as the predominant cell type present in the peripheral blood of both male and female mice, comprising 75–90% of the total leukocytes. While no significant differences were observed between male and female differential counts of blood collected from saphenous and tail veins, a significant difference in differential counts of blood obtained via cardiac puncture was observed between the male and female groups, suggesting the role of sex hormones. Further, of the four methods, cardiac puncture appeared to be the fastest and more reliable technique, yielding

  13. Capillary pericytes regulate cerebral blood flow in health and disease

    DEFF Research Database (Denmark)

    Hall, Catherine N; Reynell, Clare; Gesslein, Bodil


    Increases in brain blood flow, evoked by neuronal activity, power neural computation and form the basis of BOLD (blood-oxygen-level-dependent) functional imaging. Whether blood flow is controlled solely by arteriole smooth muscle, or also by capillary pericytes, is controversial. We demonstrate...... blood flow, capillaries dilate before arterioles and are estimated to produce 84% of the blood flow increase. In pathology, ischaemia evokes capillary constriction by pericytes. We show that this is followed by pericyte death in rigor, which may irreversibly constrict capillaries and damage the blood......-brain barrier. Thus, pericytes are major regulators of cerebral blood flow and initiators of functional imaging signals. Prevention of pericyte constriction and death may reduce the long-lasting blood flow decrease that damages neurons after stroke....

  14. Intramuscular blood flow quantification with power doppler ultrasonography. (United States)

    Dori, Amir; Abbasi, Hiba; Zaidman, Craig M


    Quantification of blood flow to muscle using ultrasound is limited to large vessels. Small vessel intramuscular blood flow cannot be quantified using ultrasound without specialized methods or intravenous contrast. We describe a technique using power Doppler to quantify postcontraction hyperemia in intramuscular vessels that can be used at the bedside. In 11 healthy subjects, postcontraction intramuscular blood flow in the forearm flexors and tibialis anterior muscles increased with stronger and repeated contractions. Intravascular blood flow measured by pulsed Doppler in the brachial artery similarly increased. Three patients with muscular dystrophies showed a negligible increase of postcontraction intramuscular blood flow. Intramuscular blood flow can be quantified using power Doppler ultrasonography; it increases following contraction and may be reduced in patients with muscular dystrophies. This quantitative, noninvasive technique can be applied at the bedside and may facilitate studies of disease impact on intramuscular blood flow. Muscle Nerve 54: 872-878, 2016. © 2016 Wiley Periodicals, Inc.

  15. Portal Vein Thrombosis (United States)

    Chawla, Yogesh K.; Bodh, Vijay


    Portal vein thrombosis is an important cause of portal hypertension. PVT occurs in association with cirrhosis or as a result of malignant invasion by hepatocellular carcinoma or even in the absence of associated liver disease. With the current research into its genesis, majority now have an underlying prothrombotic state detectable. Endothelial activation and stagnant portal blood flow also contribute to formation of the thrombus. Acute non-cirrhotic PVT, chronic PVT (EHPVO), and portal vein thrombosis in cirrhosis are the three main variants of portal vein thrombosis with varying etiological factors and variability in presentation and management. Procoagulant state should be actively investigated. Anticoagulation is the mainstay of therapy for acute non-cirrhotic PVT, with supporting evidence for its use in cirrhotic population as well. Chronic PVT (EHPVO) on the other hand requires the management of portal hypertension as such and with role for anticoagulation in the setting of underlying prothrombotic state, however data is awaited in those with no underlying prothrombotic states. TIPS and liver transplant may be feasible even in the setting of PVT however proper selection of candidates and type of surgery is warranted. Thrombolysis and thrombectomy have some role. TARE is a new modality for management of HCC with portal vein invasion. PMID:25941431

  16. A Computational Framework to Optimize Subject-Specific Hemodialysis Blood Flow Rate to Prevent Intimal Hyperplasia (United States)

    Mahmoudzadeh, Javid; Wlodarczyk, Marta; Cassel, Kevin


    Development of excessive intimal hyperplasia (IH) in the cephalic vein of renal failure patients who receive chronic hemodialysis treatment results in vascular access failure and multiple treatment complications. Specifically, cephalic arch stenosis (CAS) is known to exacerbate hypertensive blood pressure, thrombosis, and subsequent cardiovascular incidents that would necessitate costly interventional procedures with low success rates. It has been hypothesized that excessive blood flow rate post access maturation which strongly violates the venous homeostasis is the main hemodynamic factor that orchestrates the onset and development of CAS. In this article, a computational framework based on a strong coupling of computational fluid dynamics (CFD) and shape optimization is proposed that aims to identify the effective blood flow rate on a patient-specific basis that avoids the onset of CAS while providing the adequate blood flow rate required to facilitate hemodialysis. This effective flow rate can be achieved through implementation of Miller's surgical banding method after the maturation of the arteriovenous fistula and is rooted in the relaxation of wall stresses back to a homeostatic target value. The results are indicative that this optimized hemodialysis blood flow rate is, in fact, a subject-specific value that can be assessed post vascular access maturation and prior to the initiation of chronic hemodialysis treatment as a mitigative action against CAS-related access failure. This computational technology can be employed for individualized dialysis treatment.

  17. Cerebral blood flow tomography with xenon-133

    Energy Technology Data Exchange (ETDEWEB)

    Lassen, N.A.


    Cerebral blood flow (CBF) can be measured tomographically by inhalation of Xenon-/sup 133/. The calculation is based on taking a sequence of tomograms during the wash-in and wash-out phase of the tracer. Due to the dynamic nature of the process, a highly sensitive and fast moving single photon emission computed tomograph (SPECT) is required. Two brain-dedicated SPECT systems designed for this purpose are mentioned, and the method is described with special reference to the limitations inherent in the soft energy of the 133Xe primary photons. CBF tomography can be used for a multitude of clinical and investigative purposes. This article discusses in particular its use for the selection of patients with carotid occlusion for extracranial/intracranial bypass surgery, for detection of severe arterial spasm after aneurysm bleeding, and for detection of low flow areas during severe migraine attacks. The use of other tracers for CBF tomography using SPECT is summarized with emphasis on the /sup 99m/Tc chelates that freely pass the intact blood-brain barrier. The highly sensitive brain-dedicated SPECT systems described are a prerequisite for achieving high resolution tomograms with such tracers.

  18. Portal vein resection and reconstruction with artificial blood vessels is safe and feasible for pancreatic ductal adenocarcinoma patients with portal vein involvement: Chinese center experience. (United States)

    Xie, Zhi-Bo; Gu, Ji-Chun; Zhang, Yi-Fan; Yao, Lie; Jin, Chen; Jiang, Yong-Jian; Li, Ji; Yang, Feng; Zou, Cai-Feng; Fu, De-Liang


    Evidence shows that portal vein resection (PVR) increase the resectability but does little benefit to overall survival in all pancreatic ductal adenocarcinoma (PDAC) patients. But for patients with portal vein involvement, PVR is the only radical choice. But whether the PDAC patients with portal vein involvement would benefit from radical pancreaticoduodenectomy with PVR or not is controversial. All 204 PDAC patients with portal vein involvement were enrolled in this study [PVR group, n=106; surgical bypass (SB) group, n=52; chemotherapy group, n=46]. Overall survival and prognostic factors were analyzed among three groups. Moreover, a literature review of 13 studies were also conducted. Among 3 groups, patients in PVR group achieved a significant longer survival (median survival: PVR group, 22.83 months; SB group, 7.26 months; chemotherapy group, 10.64 months). Therapy choice [hazard ratio (HR) =1.593, 95% confidence interval (CI) 1.323 to 1.918, Pportal vein involvement.

  19. The effect of hyperosmotic solutions on the hepatic blood flow

    DEFF Research Database (Denmark)

    Winkler, K; Henriksen, Jens Henrik Sahl; Tygstrup, N


    The present study was undertaken in order to measure the effect of hyperosmotic solutions on portal and hepatic blood flow. In five anaesthetized pigs without arterial blood supply to the liver, portal blood flow rate was measured (electromagnetic flowmeter) during 5 min lasting intravenous...... for these osmotic effects are not known, but they have to be taken into consideration in studies of the portal and hepatic blood flow....

  20. Remodelling of choroidal blood flow in radiation choroidopathy

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Hideo; Muraoka, Kanemitsu; Takahashi, Kyoichi; Sutoh, Noriko [Gunma Univ., Maebashi (Japan). School of Medicine


    Two males, aged 68 and 34 years each, presented with radiation retinopathy. One had received radiation therapy to the whole brain for intracranial metastasis of lung carcinoma 29 months before. The other underwent surgery and radiation for melanoma of the upper eyelid 15 years before. When examined by indocyanine green angiography. both cases showed vasoocclusive changes in the choroid involving the choriocapillaris and major vessels in the affected fundus area. In one eye with severe retinal vascular lesions in the superior temporal quadrant, the vortex vein in the quadrant had obliterated. The venous blood in this quadrant was drained into the inferior temporal vortex vein crossing the presumed watershed zone temporal to the macula. Collaterals had formed between choroidal arteries and between choroidal veins. These cases illustrate that choroidal vascular lesions may be present in radiation retinopathy, that the former may be more pronounced than the latter and that choroidal vessels may undergo extensive remodelling to compensate for the disturbed choroidal circulation. (author)

  1. Advanced Recording and Preprocessing of Physiological Signals. [data processing equipment for flow measurement of blood flow by ultrasonics (United States)

    Bentley, P. B.


    The measurement of the volume flow-rate of blood in an artery or vein requires both an estimate of the flow velocity and its spatial distribution and the corresponding cross-sectional area. Transcutaneous measurements of these parameters can be performed using ultrasonic techniques that are analogous to the measurement of moving objects by use of a radar. Modern digital data recording and preprocessing methods were applied to the measurement of blood-flow velocity by means of the CW Doppler ultrasonic technique. Only the average flow velocity was measured and no distribution or size information was obtained. Evaluations of current flowmeter design and performance, ultrasonic transducer fabrication methods, and other related items are given. The main thrust was the development of effective data-handling and processing methods by application of modern digital techniques. The evaluation resulted in useful improvements in both the flowmeter instrumentation and the ultrasonic transducers. Effective digital processing algorithms that provided enhanced blood-flow measurement accuracy and sensitivity were developed. Block diagrams illustrative of the equipment setup are included.

  2. Retrograde portal vein flow and transarterial chemoembolization in patients with hepatocellular carcinoma - a case-control study. (United States)

    Kirstein, Martha M; Voigtländer, Torsten; Schweitzer, Nora; Gebel, Michael; Hinrichs, Jan B; Rodt, Thomas; Manns, Michael P; Wacker, Frank; Potthoff, Andrej; Vogel, Arndt


    Transarterial chemoembolization (TACE) is the most common treatment for hepatocellular carcinoma (HCC). In case of portal vein (PV) flow diversion, outcome may be compromised due to a decompensation of hepatic perfusion following arterial embolization. The aim of this study was to determine whether TACE in patients with retrograde PV flow results in a stronger deterioration of liver function and a poorer survival compared to patients with orthograde PV flow. A database of 606 patients treated with TACE between 2000 and 2015 at Hannover Medical School was screened for Doppler ultrasound (US) findings on PV flow prior to TACE. A total of 407 patients were identified, among which 32 patients had retrograde PV flow. Patients with retrograde PV flow had significantly more often liver cirrhosis with advanced hepatic dysfunction (93.5% vs. 72.7%, p flow, respectively (HR 1.27, p > .05). Patients with retrograde PV flow showed a trend for a shorter OS when matched for cirrhosis (12 vs. 21months, HR 1.51), Child-Pugh score/albumin-bilirubin grade (12 vs. 15 months). There was no difference in the deterioration of liver function after repeated treatments between both groups as assessed by increase of CP points and ALBI grade. Retrograde PV flow alone was not a significant prognostic marker, but patients with retrograde PV flow and advanced liver cirrhosis treated with TACE had a very short survival. Assessment of PV flow prior TACE may be helpful in borderline cases considered for TACE.

  3. Intraoperative cerebral blood flow imaging of rodents (United States)

    Li, Hangdao; Li, Yao; Yuan, Lu; Wu, Caihong; Lu, Hongyang; Tong, Shanbao


    Intraoperative monitoring of cerebral blood flow (CBF) is of interest to neuroscience researchers, which offers the assessment of hemodynamic responses throughout the process of neurosurgery and provides an early biomarker for surgical guidance. However, intraoperative CBF imaging has been challenging due to animal's motion and position change during the surgery. In this paper, we presented a design of an operation bench integrated with laser speckle contrast imager which enables monitoring of the CBF intraoperatively. With a specially designed stereotaxic frame and imager, we were able to monitor the CBF changes in both hemispheres during the rodent surgery. The rotatable design of the operation plate and implementation of online image registration allow the technician to move the animal without disturbing the CBF imaging during surgery. The performance of the system was tested by middle cerebral artery occlusion model of rats.

  4. Cerebral blood flow in normal pressure hydrocephalus

    Energy Technology Data Exchange (ETDEWEB)

    Mamo, H.L.; Meric, P.C.; Ponsin, J.C.; Rey, A.C.; Luft, A.G.; Seylaz, J.A.


    A xenon-133 method was used to measure cerebral blood flow (CBF) before and after cerebrospinal fluid (CSF) removal in patients with normal pressure hydrocephalus (NPH). Preliminary results suggested that shunting should be performed on patients whose CBF increased after CSF removal. There was a significant increase in CBF in patients with NPH, which was confirmed by the favorable outcome of 88% of patients shunted. The majority of patients with senile and presenile dementia showed a decrease or no change in CBF after CSF removal. It is suggested that although changes in CBF and clinical symptoms of NPH may have the same cause, i.e., changes in the cerebral intraparenchymal pressure, there is no simple direct relation between these two events. The mechanism underlying the loss of autoregulation observed in NPH is also discussed.

  5. Cerebral blood flow and metabolism during sleep

    DEFF Research Database (Denmark)

    Madsen, Peter Lund; Vorstrup, S


    A review of the current literature regarding sleep-induced changes in cerebral blood flow (CBF) and cerebral metabolic rate (CMR) is presented. Early investigations have led to the notion that dreamless sleep was characterized by global values of CBF and CMR practically at the level of wakefulness......, while rapid eye movement (REM) sleep (dream sleep) was a state characterized by a dramatically increased level of CBF and possibly also of CMR. However, recent investigations firmly contradict this notion. Investigations on CBF and CMR performed during non-REM sleep, taking the effect of different...... levels of sleep into consideration, show that light sleep (stage II) is characterized by global levels of CBF and CMR only slightly reduced by 3-10% below the level associated with wakefulness, whereas CBF and CMR during deep sleep (stage III-IV) is dramatically reduced by 25-44%. Furthermore, recent...

  6. Prospective association of fetal liver blood flow at 30 weeks gestation with newborn adiposity. (United States)

    Ikenoue, Satoru; Waffarn, Feizal; Ohashi, Masanao; Sumiyoshi, Kaeko; Ikenoue, Chigusa; Buss, Claudia; Gillen, Daniel L; Simhan, Hyagriv N; Entringer, Sonja; Wadhwa, Pathik D


    The production of variation in adipose tissue accretion represents a key fetal adaptation to energy substrate availability during gestation. Because umbilical venous blood transports nutrient substrate from the maternal to the fetal compartment and because the fetal liver is the primary organ in which nutrient interconversion occurs, it has been proposed that variations in the relative distribution of umbilical venous blood flow shunting either through ductus venosus or perfusing the fetal liver represents a mechanism underlying this adaptation. The objective of the present study was to determine whether fetal liver blood flow assessed before the period of maximal fetal fat deposition (ie, the third trimester of gestation) is prospectively associated with newborn adiposity. A prospective study was conducted in a cohort of 62 uncomplicated singleton pregnancies. Fetal ultrasonography was performed at 30 weeks gestation for conventional fetal biometry and characterization of fetal liver blood flow (quantified by subtracting ductus venosus flow from umbilical vein flow). Newborn body fat percentage was quantified by dual energy X-ray absorptiometry imaging at 25.8 ± 3.3 (mean ± standard error of the mean) postnatal days. Multiple regression analysis was used to determine the proportion of variation in newborn body fat percentage explained by fetal liver blood flow. Potential confounding factors included maternal age, parity, prepregnancy body mass index, gestational weight gain, gestational age at birth, infant sex, postnatal age at dual energy X-ray absorptiometry scan, and mode of infant feeding. Newborn body fat percentage was 13.5% ± 2.4% (mean ± standard error of the mean). Fetal liver blood flow at 30 weeks gestation was significantly and positively associated with newborn total fat mass (r=0.397; Pliver blood flow explained 13.5% of the variance in newborn fat mass. The magnitude of this association was pronounced particularly in nonoverweight

  7. Localization of Short-Chain Polyphosphate Enhances its Ability to Clot Flowing Blood Plasma (United States)

    Yeon, Ju Hun; Mazinani, Nima; Schlappi, Travis S.; Chan, Karen Y. T.; Baylis, James R.; Smith, Stephanie A.; Donovan, Alexander J.; Kudela, Damien; Stucky, Galen D.; Liu, Ying; Morrissey, James H.; Kastrup, Christian J.


    Short-chain polyphosphate (polyP) is released from platelets upon platelet activation, but it is not clear if it contributes to thrombosis. PolyP has increased propensity to clot blood with increased polymer length and when localized onto particles, but it is unknown whether spatial localization of short-chain polyP can accelerate clotting of flowing blood. Here, numerical simulations predicted the effect of localization of polyP on clotting under flow, and this was tested in vitro using microfluidics. Synthetic polyP was more effective at triggering clotting of flowing blood plasma when localized on a surface than when solubilized in solution or when localized as nanoparticles, accelerating clotting at 10-200 fold lower concentrations, particularly at low to sub-physiological shear rates typical of where thrombosis occurs in large veins or valves. Thus, sub-micromolar concentrations of short-chain polyP can accelerate clotting of flowing blood plasma under flow at low to sub-physiological shear rates. However, a physiological mechanism for the localization of polyP to platelet or vascular surfaces remains unknown.

  8. Correlation between the milk vein internal diameter surface andmilk yield in Simmental cows




    It is known that milk production is directly correlated with the blood flow through the mammary gland, and milk veins drain approximately 90% of the total blood passing through this organ. The aim of the present study was to determine the relationship between milk vein internal diameter surface and milk production in Simmental cows. The milk vein internal diameter was measured by ultrasonography in heifers during the 2nd month of the first gravidity, and again on day 50 following the second c...

  9. Remifentanil decreases oral tissue blood flow while maintaining internal carotid artery blood flow during sevoflurane anesthesia in rabbits. (United States)

    Hirata, Atsushi; Kasahara, Masataka; Matsuura, Nobuyuki; Ichinohe, Tatsuya


    The aim of this study was to investigate the effect of remifentanil infusion on oral tissue blood flow including submandibular gland tissue blood flow (SBF) and internal carotid artery blood flow (ICBF) in rabbits during sevoflurane anesthesia. Twelve male Japan White rabbits were anesthetized with sevoflurane and remifentanil. Remifentanil was infused at 0.2 and 0.4 µg/kg/min. Measurements included circulatory variables, common and external carotid artery blood flow (CCBF, ECBF), ICBF, tongue mucosal blood flow (TMBF), masseter muscle tissue blood flow (MBF), mandibular bone marrow tissue blood flow (BBF), tongue muscle tissue blood flow (TBF), and SBF. Vascular resistances for each tissue, including the tongue mucosa, masseter muscle, mandibular bone marrow, tongue muscle, and submandibular gland, were calculated by dividing the mean arterial pressure by the respective tissue blood flow. Remifentanil infusion decreased oral tissue blood flow and circulatory variables. CCBF, ECBF, and ICBF did not change. The calculated vascular resistance in each oral tissue, except for the tongue mucosa, increased in an infusion-rate-dependent manner. These results showed that remifentanil infusion reduced TMBF, MBF, BBF, TBF, and SBF in an infusion-rate-dependent manner without affecting ICBF under sevoflurane anesthesia.

  10. Dopexamine increases internal mammary artery blood flow following coronary artery bypass grafting.

    LENUS (Irish Health Repository)

    Flynn, Michael J


    OBJECTIVE: Vasoactive agents and inotropes influence conduit-coronary blood flow following coronary artery bypass grafting (CABG). It was hypothesized that dopexamine hydrochloride, a dopamine A-1 (DA-1) and beta(2) agonist would increase conduit-coronary blood flow. A prospective randomized double blind clinical trial was carried out to test this hypothesis. DA-1 receptors have previously been localized to human left ventricle. METHODS: Twenty-six American Society of Anaesthesiology class 2-3 elective coronary artery bypass graft patients who did not require inotropic support on separation from cardiopulmonary bypass (CPB) were studied. According to a randomized allocation patients received either dopexamine (1 microg\\/kg per min) or placebo (saline) by intravenous infusion for 15 min. Immediately prior to and at 5,10 and 15 min of infusion, blood flow through the internal mammary and vein grafts (Transit time flow probes, Transonic Ltd.), heart rate, cardiac index, mean arterial pressure and pulmonary haemodynamics were noted. The data were analysed using multivariate analysis of variance. RESULTS: Low-dose dopexamine (1 microg\\/kg per min) caused a significant increase in mammary graft blood flow compared to placebo at 15 min of infusion (P=0.028, dopexamine group left internal mammary artery (LIMA) flow of 43.3+\\/-14.2 ml\\/min, placebo group LIMA flow at 26.1+\\/-16.3 ml\\/min). Dopexamine recipients demonstrated a non-significant trend to increased saphenous vein graft flow (P=0.059). Increased heart rate was the only haemodynamic change induced by dopexamine (P=0.004, dopexamine group at 85.2+\\/-9.6 beats\\/min and placebo group at 71.1+\\/-7.6 beats\\/min after 15 min of infusion). CONCLUSION: This study demonstrates that administration of dopexamine (1 microg\\/kg per min) was associated with a significant increase in internal mammary artery graft blood flow with mild increase in heart rate being the only haemodynamic change. Low-dose dopexamine may

  11. En face Doppler total retinal blood flow measurement with 70 kHz spectral optical coherence tomography (United States)

    Tan, Ou; Liu, Gangjun; Liang, Liu; Gao, Simon S.; Pechauer, Alex D.; Jia, Yali; Huang, David


    Abstract. An automated algorithm was developed for total retinal blood flow (TRBF) using 70-kHz spectral optical coherence tomography (OCT). The OCT was calibrated for the transformation from Doppler shift to speed based on a flow phantom. The TRBF scan pattern contained five repeated volume scans (2×2  mm) obtained in 3 s and centered on central retinal vessels in the optic disc. The TRBF was calculated using an en face Doppler technique. For each retinal vein, blood flow was measured at an optimal plane where the calculated flow was maximized. The TRBF was calculated by summing flow in all veins. The algorithm tracked vascular branching so that either root or branch veins are summed, but never both. The TRBF in five repeated volumes were averaged to reduce variation due to cardiac cycle pulsation. Finally, the TRBF was corrected for eye length variation. Twelve healthy eyes and 12 glaucomatous eyes were enrolled to test the algorithm. The TRBF was 45.4±6.7  μl/min for healthy control and 34.7±7.6  μl/min for glaucomatous participants (p-value=0.01). The intravisit repeatability was 8.6% for healthy controls and 8.4% for glaucoma participants. The proposed automated method provided repeatable TRBF measurement. PMID:26062663

  12. Effect of glomerulopressin on ovarian blood flow in dogs. (United States)

    Uranga, J; Del Castillo, E


    The present study showed that glomerulopressin decreased ovarian blood flow in normal dogs and that this effect could be inhibited by treatment with indomethacin. In addition diabetic dogs had a high plasma level of glomerulopressin and a low ovarian blood flow that was shown to increase after treatment with indomethacin. This suggests that the low ovarian blood flow in diabetis might be due to a prostaglandin synthesizing effect of glomerulopressin.

  13. The vertebral venous plexuses: the internal veins are muscular and external veins have valves. (United States)

    Stringer, Mark D; Restieaux, Matthew; Fisher, Amanda L; Crosado, Brynley


    The internal and external vertebral venous plexuses (VVP) extend the length of the vertebral column. Authoritative sources state that these veins are devoid of valves, permitting bidirectional blood flow and facilitating the hematogenous spread of malignant tumors that have venous connections with these plexuses. The aim of this investigation was to identify morphologic features that might influence blood flow in the VVP. The VVP of 12 adult cadavers (seven female, mean age 79.5 years) were examined by macro- and micro-dissection and representative veins removed for histology and immunohistochemistry (smooth muscle antibody staining). A total of 26, mostly bicuspid, valves were identified in 19 of 56 veins (34%) from the external VVP, all orientated to promote blood flow towards the internal VVP. The internal VVP was characterized by four main longitudinal channels with transverse interconnections; the maximum caliber of the longitudinal anterior internal VVP veins was significantly greater than their posterior counterparts (P < 0.001). The luminal architecture of the internal VVP veins was striking, consisting of numerous bridging trabeculae (cords, thin membranes and thick bridges) predominantly within the longitudinal venous channels. Trabeculae were composed of collagen and smooth muscle and also contained numerous small arteries and nerve fibers. A similar internal venous trabecular meshwork is known to exist within the dural venous sinuses of the skull. It may serve to prevent venous overdistension or collapse, to regulate the direction and velocity of venous blood flow, or is possibly involved in thermoregulation or other homeostatic processes. © 2011 Wiley Periodicals, Inc.

  14. Dynamic Effect of Rolling Massage on Blood Flow (United States)

    Chen, Yan-Yan; Yi, Hou-Hui; Li, Hua-Bing; Fang, Hai-Ping


    The Chinese traditional medical massage has been used as a natural therapy to eliminate some diseases. Here, the effect of the rolling massage frequency to the blood flow in the blood vessels under the rolling massage manipulation is studied by the lattice Boltzmann simulation. The simulation results show that when the frequency is smaller than or comparable to the pulsatile frequency of the blood flow, the effect on the blood flux by the rolling massage is small. On the contrast, if the frequency is twice or more times of the pulsatile frequency of the blood flow, the blood flux is greatly enhanced and increases linearly with respect to the frequency. Similar behavior has also been observed on the shear stress on the blood vessel walls. The result is helpful for understanding that the rolling massage has the function of promoting the blood circulation and removing the blood stasis.

  15. Reflux venous flow in dural sinus and internal jugular vein on 3D time-of-flight MR angiography

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Jinhee; Kim, Bum-soo; Kim, Bom-yi; Choi, Hyun Seok; Jung, So-Lyung; Ahn, Kook-Jin; Byun, Jae Young [The Catholic University of Korea, Department of Radiology, Seoul St. Mary' s Hospital, School of Medicine, Seoul (Korea, Republic of)


    Reflux venous signal on the brain and neck time-of-flight magnetic resonance angiography (TOF MRA) is thought to be related to a compressed left brachiocephalic vein. This study is aimed to assess the prevalence of venous reflux flow in internal jugular vein (IJV), sigmoid sinus/transverse sinus (SS/TS), and inferior petrosal sinus (IPS) on the brain and neck TOF MRA and its pattern. From the radiology database, 3,475 patients (1,526 men, 1,949 women, age range 19-94, median age 62 years) with brain and neck standard 3D TOF MRA at 3 T and 1.5 T were identified. Rotational maximal intensity projection images of 3D TOF MRA were assessed for the presence of reflux flow in IJV, IPS, and SS/TS. Fifty-five patients (1.6 %) had reflux flow, all in the left side. It was more prevalent in females (n = 43/1,949, 2.2 %) than in males (n = 12/1,526, 0.8 %) (p = 0.001). The mean age of patients with reflux flow (66 years old) was older than those (60 years old) without reflux flow (p = 0.001). Three patients had arteriovenous shunt in the left arm for hemodialysis. Of the remaining 52 patients, reflux was seen on IJV in 35 patients (67.3 %). There were more patients with reflux flow seen on SS/TS (n = 34) than on IPS (n = 25). Venous reflux flow on TOF MRA is infrequently observed, and reflux pattern is variable. Because it is exclusively located in the left side, the reflux signal on TOF MRA could be an alarm for an undesirable candidate for a contrast injection on the left side for contrast-enhanced imaging study. (orig.)

  16. Daily rhythm of cerebral blood flow velocity

    Directory of Open Access Journals (Sweden)

    Spielman Arthur J


    Full Text Available Abstract Background CBFV (cerebral blood flow velocity is lower in the morning than in the afternoon and evening. Two hypotheses have been proposed to explain the time of day changes in CBFV: 1 CBFV changes are due to sleep-associated processes or 2 time of day changes in CBFV are due to an endogenous circadian rhythm independent of sleep. The aim of this study was to examine CBFV over 30 hours of sustained wakefulness to determine whether CBFV exhibits fluctuations associated with time of day. Methods Eleven subjects underwent a modified constant routine protocol. CBFV from the middle cerebral artery was monitored by chronic recording of Transcranial Doppler (TCD ultrasonography. Other variables included core body temperature (CBT, end-tidal carbon dioxide (EtCO2, blood pressure, and heart rate. Salivary dim light melatonin onset (DLMO served as a measure of endogenous circadian phase position. Results A non-linear multiple regression, cosine fit analysis revealed that both the CBT and CBFV rhythm fit a 24 hour rhythm (R2 = 0.62 and R2 = 0.68, respectively. Circadian phase position of CBT occurred at 6:05 am while CBFV occurred at 12:02 pm, revealing a six hour, or 90 degree difference between these two rhythms (t = 4.9, df = 10, p Conclusion In conclusion, time of day variations in CBFV have an approximately 24 hour rhythm under constant conditions, suggesting regulation by a circadian oscillator. The 90 degree-phase angle difference between the CBT and CBFV rhythms may help explain previous findings of lower CBFV values in the morning. The phase difference occurs at a time period during which cognitive performance decrements have been observed and when both cardiovascular and cerebrovascular events occur more frequently. The mechanisms underlying this phase angle difference require further exploration.

  17. Portal vein stent placement for the treatment of postoperative portal vein stenosis: long-term success and factor associated with stent failure. (United States)

    Kato, Atsushi; Shimizu, Hiroaki; Ohtsuka, Masayuki; Yoshitomi, Hideyuki; Furukawa, Katsunori; Miyazaki, Masaru


    Portal vein stenosis develops due to different causes including postoperative inflammation and oncological processes. However, limited effective therapy is available for portal vein stenosis. The objectives of this study were to evaluate the efficacy of a portal vein stent for portal vein stenosis after hepatobiliary pancreatic surgery and to determine the factors associated with stent patency. From December 2003 to December 2015, portal vein stents were implanted in 29 patients who had portal vein stenosis after hepatobiliary pancreatic surgery. We conducted a retrospective analysis to evaluate the efficacy and safety of portal vein stent placement. Twelve clinical variables were analyzed for their role in stent patency. The symptoms before portal vein stent placements included nine patients with hepatic encephalopathy, six patients with gastrointestinal bleeding, four patients with ascites, and four patients with hyperbilirubinemia. Portal vein thrombosis due to postoperative portal stenosis was found in four patients. Portal vein stent were successfully implanted without any major complications. Of the 21 patients with symptoms, 17 showed improvement, and stent patency was maintained in 22 (76%) patients. The presence of a collateral vein is the only variable related to the development of an occlusion after portal stenting. Portal vein stent were implanted safely and had good long-term patency. This procedure is useful to relieve portal hypertension-related symptoms and to improve the quality of life. Our data strongly suggest that embolization to block blood flow in a collateral vein during portal vein stent placement will improve the patency of the stent.


    NARCIS (Netherlands)


    In chronic hypoxemia blood flow and oxygen supply to vital organs are maintained, but to nonvital organs they are decreased. We measured organ blood flows (microspheres) and whole blood viscosity in 10 chronically hypoxemic lambs, with an atrial septal defect and pulmonary stenosis, and in 8 control

  19. Subcutaneous blood flow during insulin-induced hypoglycaemia

    DEFF Research Database (Denmark)

    Hilsted, J; Madsbad, S; Sestoft, L


    Subcutaneous blood flow was measured preceding insulin-induced hypoglycaemia, at the onset of hypoglycaemic symptoms and 2 h later in juvenile diabetics with and without autonomic neuropathy and in normal males. In all groups subcutaneous blood flow decreased at the onset of hypoglycaemic symptoms...... compared with pre-hypoglycaemic flow. Two hours after onset of hypoglycaemic symptoms, subcutaneous blood flow was still significantly decreased compared with pre-hypoglycaemic flow. In normal subjects local nerve blockade had no effect on blood flow changes during hypoglycaemia, whereas local alpha......-receptor blockade abolished the vasoconstrictor response. We suggest that circulating catecholamines stimulating vascular alpha-receptors are probably responsible for flow reduction in the subcutaneous tissue during hypoglycaemia....

  20. Blood flow restricted exercise and vascular function. (United States)

    Horiuchi, Masahiro; Okita, Koichi


    It is established that regular aerobic training improves vascular function, for example, endothelium-dependent vasodilatation and arterial stiffness or compliance and thereby constitutes a preventative measure against cardiovascular disease. In contrast, high-intensity resistance training impairs vascular function, while the influence of moderate-intensity resistance training on vascular function is still controversial. However, aerobic training is insufficient to inhibit loss in muscular strength with advancing age; thus, resistance training is recommended to prevent sarcopenia. Recently, several lines of study have provided compelling data showing that exercise and training with blood flow restriction (BFR) leads to muscle hypertrophy and strength increase. As such, BFR training might be a novel means of overcoming the contradiction between aerobic and high-intensity resistance training. Although it is not enough evidence to obtain consensus about impact of BFR training on vascular function, available evidences suggested that BFR training did not change coagulation factors and arterial compliance though with inconsistence results in endothelial function. This paper is a review of the literature on the impact of BFR exercise and training on vascular function, such as endothelial function, arterial compliance, or other potential factors in comparison with those of aerobic and resistance training.

  1. Suboccipital dermatomyotomic stimulation and digital blood flow. (United States)

    Purdy, W R; Frank, J J; Oliver, B


    The effect of gentle, soft tissue manipulation in the suboccipital region on digital blood flow, as a measure of sympathetic nervous system activity, was studied. Digital strain gauge plethysmography was used to measure the changes in pulse contour during (1) a normative test period with the subject in the supine position, (2) after a control interval (placebo) during which the investigator placed his hands under the suboccipital region, and (3) after an interval during which the investigator's fingers applied slow, steady, circular kneading in the suboccipital triangle region. Twenty-five studies were performed in a crossover design with the patient as his or her own control. Total pulse amplitude (Y) and the height from the dicrotic notch to the peak (X) were measured. Examination of the total data of all subjects revealed the occurrence of a significant change in X and Y with simply touching the suboccipital region with the hands. An even more favorable response ensued when suboccipital manipulation was applied. Those subjects reporting comfort or neutral responses had larger significant changes with manipulation when compared with the group reporting the experience as uncomfortable. The response within each group suggests that favorable autonomic changes (sympathetic dampening) occur with specific suboccipital manipulation as well as, indeed, the simple touching of the suboccipital triangle.

  2. Blood Flow Restricted Exercise and Vascular Function

    Directory of Open Access Journals (Sweden)

    Masahiro Horiuchi


    Full Text Available It is established that regular aerobic training improves vascular function, for example, endothelium-dependent vasodilatation and arterial stiffness or compliance and thereby constitutes a preventative measure against cardiovascular disease. In contrast, high-intensity resistance training impairs vascular function, while the influence of moderate-intensity resistance training on vascular function is still controversial. However, aerobic training is insufficient to inhibit loss in muscular strength with advancing age; thus, resistance training is recommended to prevent sarcopenia. Recently, several lines of study have provided compelling data showing that exercise and training with blood flow restriction (BFR leads to muscle hypertrophy and strength increase. As such, BFR training might be a novel means of overcoming the contradiction between aerobic and high-intensity resistance training. Although it is not enough evidence to obtain consensus about impact of BFR training on vascular function, available evidences suggested that BFR training did not change coagulation factors and arterial compliance though with inconsistence results in endothelial function. This paper is a review of the literature on the impact of BFR exercise and training on vascular function, such as endothelial function, arterial compliance, or other potential factors in comparison with those of aerobic and resistance training.

  3. Regional cerebral blood flow in focal cortical epilepsy

    DEFF Research Database (Denmark)

    Hougaard, Kristina Dupont; Oikawa, T; Sveinsdottir, E


    Regional cerebral blood flow (rCBF) was studied in ten patients with focal cortical epilepsy. The blood flow was measured by the intra-arterial injection of xenon 133 (133Xe), and the isotope clearance was recorded by a multidetector scintillation camera with 254 detectors. Three patients were st...

  4. Cholinesterase inhibition improves blood flow in the ischemic cerebral cortex. (United States)

    Scremin, O U; Li, M G; Scremin, A M; Jenden, D J


    The ability of central cholinesterase inhibition to improve cerebral blood flow in the ischemic brain was tested in Sprague-Dawley rats with tandem occlusion of left middle cerebral and common carotid arteries. Cerebral blood flow was measured with lodo- 14C-antipyrine autoradiography in 170 regions of cerebral cortex. The regional distribution of blood flow was characterized in normal animals by cerebral blood flow maxima in the temporal regions. After 2 h ischemia, minimum cerebral blood flow values were found in the lateral frontal and parietal areas on the left hemisphere, and a new maximum was found in the right hemisphere in an area approximately symmetrical to the ischemic focus. Heptyl-physostigmine (eptastigmine), a carbamate cholinesterase inhibitor with prolonged time of action improved cerebral blood flow in most regions, with the exception of the ischemic core. The drug also enhanced the ischemia-induced rostral shift of cerebral blood flow maxima in the right hemisphere. The effects of eptastigmine were more marked 24 h after ischemia. Discriminant analysis showed that data from only 22 regions was sufficient to achieve 100% accuracy in classifying all cases into the various experimental conditions. The redistribution of cerebral blood flow to the sensorimotor area of the right hemisphere of animals with cerebral ischemia, a phenomenon possibly related to recovery of function, was also enhanced by eptastigmine.

  5. Self-separation of blood plasma from whole blood during the capillary flow in microchannel (United States)

    Nunna, Bharath Babu; Zhuang, Shiqiang; Lee, Eon Soo


    Self-separation of blood plasma from whole blood in microchannels is of great importance due to the enormous range of applications in healthcare and diagnostics. Blood is a multiphase complex fluid, composed of cells suspended in blood plasma. RBCs are the suspended particles whose shape changes during the flow of blood. The primary constituents of blood are erythrocytes or red blood cells (RBCs), leukocytes or white blood cells (WBCs), thrombocytes or platelets and blood plasma. The existence of RBCs in blood makes the blood a non-Newtonian fluid. The current study of separation of blood plasma from whole blood during self-driven flows in a single microchannel without bifurcation, by enhancing the capillary effects. The change in the capillary effect results in a change in contact angle which directly influences the capillary flow. The flow velocity directly influences the net force acting on the RBCs and influence the separation process. The experiments are performed on the PDMS microchannels with different contact angles by altering the surface characteristics using plasma treatment. The change in the separation length is studied during the capillary flow of blood in microchannel. Bharath Babu Nunna is a researcher in mechanical engineering and implementing the novel and innovative technologies in the biomedical devices to enhance the sensitivity of the disease diagnosis.

  6. Conditions of microvessel occlusion for blood coagulation in flow. (United States)

    Bouchnita, A; Galochkina, T; Kurbatova, P; Nony, P; Volpert, V


    Vessel occlusion is a perturbation of blood flow inside a blood vessel because of the fibrin clot formation. As a result, blood circulation in the vessel can be slowed down or even stopped. This can provoke the risk of cardiovascular events. In order to explore this phenomenon, we used a previously developed mathematical model of blood clotting to describe the concentrations of blood factors with a reaction-diffusion system of equations. The Navier-Stokes equations were used to model blood flow, and we treated the clot as a porous medium. We identify the conditions of partial or complete occlusion in a small vessel depending on various physical and physiological parameters. In particular, we were interested in the conditions on blood flow and diameter of the wounded area. The existence of a critical flow velocity separating the regimes of partial and complete occlusion was demonstrated through the mathematical investigation of a simplified model of thrombin wave propagation in Poiseuille flow. We observed different regimes of vessel occlusion depending on the model parameters both for the numerical simulations and in the theoretical study. Then, we compared the rate of clot growth in flow obtained in the simulations with experimental data. Both of them showed the existence of different regimes of clot growth depending on the velocity of blood flow. Copyright © 2016 John Wiley & Sons, Ltd.

  7. Effect of pulsatile swirling flow on stenosed arterial blood flow. (United States)

    Ha, Hojin; Lee, Sang Joon


    The existence of swirling flow phenomena is frequently observed in arterial vessels, but information on the fluid-dynamic roles of swirling flow is still lacking. In this study, the effects of pulsatile swirling inlet flows with various swirling intensities on the flow field in a stenosis model are experimentally investigated using a particle image velocimetry velocity field measurement technique. A pulsatile pump provides cyclic pulsating inlet flow and spiral inserts with two different helical pitches (10D and 10/3D) induce swirling flow in the stenosed channel. Results show that the pulsatile swirling flow has various beneficial effects by reducing the negative wall shear stress, the oscillatory shear index, and the flow reverse coefficient at the post-stenosis channel. Temporal variations of vorticity fields show that the short propagation length of the jet flow and the early breakout of turbulent flow are initiated as the swirling flow disturbs the symmetric development of the shear layer. In addition, the overall energy dissipation rate of the flow is suppressed by the swirling component of the flow. The results will be helpful for elucidating the hemodynamic characteristics of atherosclerosis and discovering better diagnostic procedures and clinical treatments. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

  8. On the flow dependency of the electrical conductivity of blood

    NARCIS (Netherlands)

    Hoetink, AE; Faes, TJC; Visser, KR; Heethaar, RM

    Experiments presented in the literature show that the electrical conductivity of flowing blood depends on flow velocity. The aim of this study is to extend the Maxwell-Fricke theory, developed for a dilute suspension of ellipsoidal particles in an electrolyte, to explain this flow dependency of the

  9. Effects of Pulsatile Blood Flow on Oxygenator Performance. (United States)

    Schraven, Lotte; Kaesler, Andreas; Flege, Christian; Kopp, Rüdger; Schmitz-Rode, Thomas; Steinseifer, Ulrich; Arens, Jutta


    Extracorporeal membrane oxygenation (ECMO) is mainly used for the therapy of acute respiratory distress syndrome and chronic obstructive lung disease. In the last years, the development of these systems underwent huge steps in optimization, but there are still problems with thrombus formation, clogging, and thus insufficient gas exchange. One idea of ECMO optimization is a pulsatile blood flow through the oxygenator, but this is still a controversy discussion. Analyzing available publications, it was not possible to identify a general statement about the effect of pulsatile blood flow on the gas exchange performance. The variety of parameters and circuit components have such a high influence on the outcome that a direct comparison of the studies is difficult. For this reason, we performed a structured study to evaluate the effects of pulsatile blood flow on the gas exchange performance of oxygenator. In in vitro tests according to DIN EN ISO 7199, we tested a small oxygenator (0.25 m 2 exchange surface, polymethylpentene fibers, 33 mL priming volume) with constant and pulsatile blood flow in comparison. Therefore, we varied the mean blood flow from 250 to 1200 mL/min, the amplitude of 0, 20, and 50%, and the frequency of 30, 60, and 90 bpm. The results demonstrate that the gas transfer for pulsatile and constant blood flow was similar (oxygen: 36-64 mL O2 /L Blood ; carbon dioxide 35-80 mL CO2 /L Blood ) for the same mean blood flow ranges. Over all, the results and analyses showed a statistically nonsignificant difference between pulsatile and nonpulsatile flow. Consequently, we conclude that the implementation of pulsatile blood flow has only a small to no effect on the gas exchange performance in an oxygenator. As the results were obtained using an oxygenator with a coiled fiber bundle, the test must be verified for a stacked fiber oxygenator. © 2018 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  10. "The blood fights on in other veins": Norman Bethune and the transfusion of cadaver blood in the Spanish Civil War. (United States)

    Lethbridge, David


    During the Spanish Civil War, Dr. Norman Bethune instituted a research laboratory to determine whether the blood from cadavers could be transfused into wounded soldiers and civilians at the front. Dr. Herman J. Muller joined him in this effort carrying out extensive experimentation into the technique and practice of such transfusions. At the same time, Bethune was in frequent contact with Dr. Reginald Saxton who later publicly advocated that the Spanish government should organize a large-scale supply of cadaver blood to the front-line hospitals. Recent evidence suggests that Saxton carried out cadaveric transfusions to an extent not previously recognized.

  11. Visualization of the superior opthalmic vein on carotid angiography

    Energy Technology Data Exchange (ETDEWEB)

    Servo, A.


    Visualization of the superior ophthalmic vein (SOV) on carotid angiography was investigated based on a prospective sample of 452 carotid angiograms performed during one year. The SOV with normal blood flow direction, from facial veins into the cavernous sinus (CS), was seen on 26% and with reversed flow direction in 7% of the angiograms. A hypothesis was suggested that the anatomical variations of the moddle cerebral (MCV) and uncal veins (UV) affected the visualization. When both the MCV and UV drained into the CS, the SOV was seen in 11% of 179 angiograms. If the MCV and UV bypassed the CS, the SOV was seen on 51% of 118 angiograms. The difference is significant. Intubation of the patient increased the visualization of the SOV with normal flow direction but did not affect the visualization of the SOV with reversed flow. No SOV with normal blood flow direction was seen on selective internal carotid angiography.

  12. A microcomputer system for assessment of peripheral blood flow. An example of nasal blood flow. (United States)

    Grönfors, T; Pyykkö, I; Aalto, H; Juhola, M; Ishizaki, H


    We have designed and implemented a microcomputer system for studying the effect of various mediator substances on the nasal blood flow. The system uses an IBM PC/AT microcomputer, which is connected with a Laser Doppler Flowmeter (LDF) and an iontophoretic drug application system. The LDF measures flux from the tissue that in the example is the inferior nasal turbinate. The flux is converted to digital form by an analog-digital converter of 12 bits. The program is implemented in the Pascal language. In the analysis, a flux level, amplitude, rise time and decay time of the pulse wave are determined. The effect of drugs on the flux can be studied by applying them iontophoretically. In the program the length and number of the drug application periods as well as the recording period are user-driven. In the nasal blood flow iontophoretically administered adrenaline reduced significantly the flux parameters and histamine canceled this effect. Tachyphylalaxis was a frequent observation in repeated measurements. The system can be used to evaluate the role of different transmitters in the etiology of chronic rhinitis.

  13. Evaluation of Placental Blood Flow in Patients with Placental Insufficiency

    Directory of Open Access Journals (Sweden)

    Julia E. Dobrokhotova


    Full Text Available Background: Placental insufficiency is a major problem of modern obstetrics due to its link to maternal and perinatal morbidity and mortality. Placental microcirculatory disorders play a decisive role in the pathogenesis of this condition. Thus, an evaluation of placental blood flow is of particular importance and crucial for appropriate diagnosis. The aim of this study was to evaluate placental blood flow in patients with placental insufficiency. SMI (superb microvascular imaging was compared to color Doppler for that purpose. Materials and Methods: Primigravida patients (n=91 at 15 to 16 weeks of gestation were enrolled. Inclusion criteria were spontaneous singleton pregnancy, age from 18 to 45 years. All participants were divided into 2 groups: Group 1 – control group (n=27 and Group 2 – threatened miscarriage group (n=64. Transvaginal ultrasound and color Doppler were performed to assess uteroplacental circulation. Placental blood flow was evaluated using a Toshiba Aplio™ 500 machine equipped with an SMI tool. Results: Placental blood flow assessment in patients with normal pregnancy revealed homogenous placental tissue, normal distribution of vessels, and active blood flow; in patients with pregnancy complications, we found inhomogeneous placenta, decreased blood flow, sporadic vessels, and avascular areas. SMI demonstrated several benefits compared to color Doppler imaging. Color Doppler allows us to assess superficial vessels only, whereas SMI provides more comprehensive data on the overall vascularization of the placenta. Conclusion: SMI by Aplio™ 500 (Toshiba may be an effective tool in the assessment of placental blood flow and the diagnosis and prognosis of placental insufficiency.

  14. Ductus venosus blood flow velocity characteristics of fetuses with single umbilical artery. (United States)

    Raio, L; Ghezzi, F; Di Naro, E; Cromi, A; Buttarelli, M; Sonnenschein, M; Dürig, P


    Sonographic Doppler evaluation of the fetal ductus venosus has been proved to be useful in the evaluation of fetal cardiac function. The aim of this study was to investigate the ductus venosus blood flow profile in fetuses with single umbilical artery and to correlate it with the umbilical cord morphology. Fetuses at >20 weeks' gestation with single umbilical artery who were otherwise healthy were consecutively enrolled into the study. The sonographic examination included evaluation of the following Doppler parameters: umbilical artery resistance index, maximum blood flow velocity of the ductus venosus during ventricular systole (S-peak) and atrial contraction (A-wave), ductus venosus time-averaged maximum velocity (TAMXV), and pulsatility index for veins (PIV). The cross-sectional area of the umbilical cord and its vessels were measured in all cases. The Doppler and morphometric values obtained were plotted on reference ranges. A total of 88 fetuses with single umbilical artery were scanned during the study period. Of these 52 met the inclusion criteria. The S-peak velocity, A-wave velocity, and TAMXV were below the 5th centile for gestational age in 57.7%, 59.6%, and 57.7% of cases, respectively. The PIV was within the normal range in 80.1% of cases. The umbilical vein cross-sectional area of fetuses with single umbilical artery was above the 95th centile for gestational age in 34.6% cases. The ductus venosus blood flow pattern is different in fetuses with single umbilical artery from that in those with a three-vessel cord. This difference may be caused in part by the particular morphology of umbilical cords with a single artery. Copyright 2003 ISUOG. Published by John Wiley & Sons, Ltd.

  15. Mesenteric, coeliac and splanchnic blood flow in humans during exercise

    DEFF Research Database (Denmark)

    Perko, M J; Nielsen, H B; Skak, C


    1. Exercise reduces splanchnic blood flow, but the mesenteric contribution to this response is uncertain. 2. In nineteen humans, superior mesenteric and coeliac artery flows were determined by duplex ultrasonography during fasting and postprandial submaximal cycling and compared with the splanchnic...... blood flow as assessed by the Indocyanine Green dye-elimination technique. 3. Cycling increased arterial pressure, heart rate and cardiac output, while it reduced total vascular resistance. These responses were not altered in the postprandial state. During fasting, cycling increased mesenteric, coeliac...... the coeliac circulation was not influenced. Postprandial cycling did not influence the mesenteric resistance significantly, but its blood flow decreased by 22 % (0.46 +/- 0.28 l min-1). Coeliac and splanchnic resistance increased by 150 and 63 %, respectively, and the corresponding regional blood flow...

  16. Mesenteric, coeliac and splanchnic blood flow in humans during exercise

    DEFF Research Database (Denmark)

    Perko, M J; Nielsen, H B; Skak, C


    1. Exercise reduces splanchnic blood flow, but the mesenteric contribution to this response is uncertain. 2. In nineteen humans, superior mesenteric and coeliac artery flows were determined by duplex ultrasonography during fasting and postprandial submaximal cycling and compared with the splanchnic...... blood flow as assessed by the Indocyanine Green dye-elimination technique. 3. Cycling increased arterial pressure, heart rate and cardiac output, while it reduced total vascular resistance. These responses were not altered in the postprandial state. During fasting, cycling increased mesenteric, coeliac...... decreased by 51 and 31 % (0.49 +/- 0.07 and 0.96 +/- 0.28 l min-1). Splanchnic blood flow values assessed by duplex ultrasound and by dye-elimination techniques were correlated (r = 0.70; P exercise in humans, splanchnic resistance increases and blood flow is reduced following...

  17. Blood Pool Agent Contrast-Enhanced MRA: Level-Set Based Artery-Vein Separation

    NARCIS (Netherlands)

    van Bemmel, C.M.; Spreeuwers, Lieuwe Jan; Verdonck, B.; Viergever, M.A.; Niessen, W.J.


    Blood pool agents (BPAs) for contrast-enhanced magnetic resonance angiography (CE-MRA) allow prolonged imaging times for higher contrast and resolution by imaging during the steady state when the contrast agent is distributed through the complete vascular system. However, simultaneous arterial and

  18. Level-Set Based Artery-Vein Separation in Blood Pool Agent CE-MR Angiograms

    NARCIS (Netherlands)

    van Bemmel, C.M.; Spreeuwers, Lieuwe Jan; Viergever, M.A.; Niessen, W.J.


    Blood pool agents (BPAs) for contrast-enhanced (CE) magnetic-resonance angiography (MRA) allow prolonged imaging times for higher contrast and resolution. Imaging is performed during the steady state when the contrast agent is distributed through the complete vascular system. However, simultaneous

  19. Determinants of coronary blood flow in sandbar sharks, Carcharhinus plumbeus. (United States)

    Cox, Georgina K; Brill, Richard W; Bonaro, Kaitlin A; Farrell, Anthony P


    The coronary circulation first appeared in the chordate lineage in cartilaginous fishes where, as in birds and mammals but unlike most teleost fishes, it supplies arterial blood to the entire myocardium. Despite the pivotal position of elasmobranch fishes in the evolution of the coronary circulation, the determinants of coronary blood flow have never been investigated in this group. Elasmobranch fishes are of special interest because of the morphological arrangement of their cardiomyocytes. Unlike teleosts, the majority of the ventricular myocardium in elasmobranch fishes is distant to the venous blood returning to the heart (i.e., the luminal blood). Also, the majority of the myocardium is in close association with the coronary circulation. To determine the relative contribution of the coronary and luminal blood supplies to cardiovascular function in sandbar sharks, Carcharhinus plumbeus, we measured coronary blood flow while manipulating cardiovascular status using acetylcholine and adrenaline. By exploring inter- and intra-individual variation in cardiovascular variables, we show that coronary blood flow is directly related to heart rate (R 2 = 0.6; P coronary blood flow is inversely related to coronary resistance both in vivo and in vitro, we suggest that in elasmobranch fishes, changes in heart rate mediate changes in coronary vascular resistance, which adjust coronary blood flow appropriately.

  20. Connexin 36 mediates blood cell flow in mouse pancreatic islets. (United States)

    Short, Kurt W; Head, W Steve; Piston, David W


    The insulin-secreting β-cells are contained within islets of Langerhans, which are highly vascularized. Blood cell flow rates through islets are glucose-dependent, even though there are no changes in blood cell flow within in the surrounding exocrine pancreas. This suggests a specific mechanism of glucose-regulated blood flow in the islet. Pancreatic islets respond to elevated glucose with synchronous pulses of electrical activity and insulin secretion across all β-cells in the islet. Connexin 36 (Cx36) gap junctions between islet β-cells mediate this synchronization, which is lost in Cx36 knockout mice (Cx36(-/-)). This leads to glucose intolerance in these mice, despite normal plasma insulin levels and insulin sensitivity. Thus, we sought to investigate whether the glucose-dependent changes in intraislet blood cell flow are also dependent on coordinated pulsatile electrical activity. We visualized and quantified blood cell flow using high-speed in vivo fluorescence imaging of labeled red blood cells and plasma. With the use of a live animal glucose clamp, blood cell flow was measured during either hypoglycemia (∼50 mg/dl) or hyperglycemia (∼300 mg/dl). In contrast to the large glucose-dependent islet blood velocity changes observed in wild-type mice, only minimal differences are observed in both Cx36(+/-) and Cx36(-/-) mice. This observation supports a novel model where intraislet blood cell flow is regulated by the coordinated electrical activity in the islet β-cells. Because Cx36 expression and function is reduced in type 2 diabetes, the resulting defect in intraislet blood cell flow regulation may also play a significant role in diabetic pathology.

  1. What is the blood flow to resting human muscle? (United States)

    Elia, M; Kurpad, A


    1. An investigation was carried out in five healthy lean adults to assess whether forearm and calf plethysmography largely reflect muscle blood flow as measured by 133Xe and whether there is substantial variability in the blood flow to muscles located at different sites in the body. 2. Blood flow to forearm and calf flexors and extensors, biceps, triceps and quadriceps was assessed using the 133Xe clearance technique. Blood flow to forearm skin and subcutaneous adipose tissue was also measured using the 133Xe clearance technique, whereas blood flow to the forearm and calf was measured using strain gauge plethysmography. 3. The mean blood flow to different muscles ranged from 1.4 +/- 0.6 (gastrocnemius) to 1.8 +/- 0.7 (forearm extensor) ml min-1 100 g-1 muscle (1.4 +/- 0.6 and 1.9 +/- 0.8 ml min-1 100 ml-1 muscle, respectively) but there were no significant differences between them. Forearm and calf blood flows (2.7 +/- 0.3 and 3.0 +/- 0.7 ml min-1 100 ml-1 limb tissue, respectively) were about 50% to more than 100% greater (P muscles within them (1.7 +/- 0.5 and 1.4 +/- 0.5 ml min-1 100 g-1 muscle, respectively, or 1.8 +/- 0.6 and 1.5 +/- 0.5 ml min-1 100 ml-1 muscle, respectively). In contrast, the blood flows to 100 g of forearm skin (9.1 +/- 2.6 ml min-1 100 g-1) and adipose tissue (3.8 +/- 1.1 ml min-1 100 g-1) were higher than the blood flow to 100 g of forearm (P < 0.01 and not significant, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Rheology of Human Blood, near and at Zero Flow (United States)

    Merrill, E. W.; Gilliland, E. R.; Cokelet, G.; Shin, H.; Britten, A.; Wells, R. E.


    Static normal human blood possesses a distinctive yield stress. When the yield stress is exceeded, the same blood has a stress-shear rate function under creeping flow conditions closely following Casson's model, which implies reversible aggregation of red cells in rouleaux and flow dominated by movement of rouleaux. The yield stress is essentially independent of temperature and its cube root varies linearly with hematocrit value. The dynamic rheological properties in the creeping flow range are such that the relative viscosity of blood to water is almost independent of temperature. Questions raised by these data are discussed, including red cell aggregation promoted by elements in the plasma. PMID:13935042

  3. Vein mechanism simulation study for deep vein thrombosis early diagnosis using cfd (United States)

    Ibrahim, Nabilah; Aziz, Nur Shazilah Abd; Manap, Abreeza Noorlina Abd


    Using a Computational Fluid Dynamics (CFD) technique, this work focus on the analysis of pressure, velocity, and vorticity of blood flow along the popliteal vein. Since the study of early stage of Deep Vein Thrombosis (DVT) becomes essential to prevent the pulmonary embolism (PE), those three parameters are analysed to assess the effect of different opening between two valves of a normal popliteal vein. When only one valve is simulated, the result of pressure shows that the highest and lowest velocities are 15.45 cm/s and 0.73 cm/s, respectively. From the visualization of observed data, however, the different size of orifice between the first and second valves influencing the velocity and vorticity of the blood flow. The rotational motion of blood particle at the same region increases the probability of blood accumulating which is associated with the development of thrombus. Thus, a series of experiment has been conducted by changing the size of valve orifice for the first and second valves along the vein distribution. The result of the CFD simulation shows a significant variation in blood flow in terms of velocity and vorticity.

  4. Copper and ceruloplasmin contents in the blood serum of peripheral and pre-hepatic veins

    Directory of Open Access Journals (Sweden)

    H. M. Canelas


    Full Text Available Copper and ceruloplasmin contents were determined in samples of peripheral and pre-hepatic venous blood of 11 patients with Manson's schistosomiasis and one patient with hepatolenticular degeneration, all of çhich submitted either to porto-caval or spleno-renal shunt. Individual difference were not significant in any of the non-Wilsonian patients. The results are discussed in regard to the current knowledge on the pathogenesis of Wilson's disease.

  5. Safety and efficacy of pulmonary vein isolation using a surround flow catheter with contact force measurement capabilities: A multicenter registry. (United States)

    Stabile, Giuseppe; Di Donna, Paolo; Schillaci, Vincenzo; Di Monaco, Antonio; Iuliano, Assunta; Caponi, Domenico; Urraro, Francesco; Solimene, Francesco; Grimaldi, Massimo; Scaglione, Marco


    Pulmonary vein (PV) isolation is the cornerstone of catheter ablation in patients with atrial fibrillation (AF). Surround flow and contact force (CF) measurement capabilities might enhance procedure efficacy and safety. We report on the safety and midterm efficacy of a novel ablation catheter for PV isolation in patients with AF. Two hundred thirty-three consecutive patients (57 ± 11 years, 76% males, 51% with structural heart disease), referred for paroxysmal (157) or persistent (76) AF, underwent PV isolation by a surround flow catheter with CF measurement capability in four centers. Ablation was guided by electroanatomic mapping allowing radiofrequency (RF) energy delivery in the antral region aiming at PV isolation. Mean overall procedure time was 100 ± 42 minutes with a mean fluoroscopy time of 6 ± 5 minutes. Mean ablation time was 31±15 minutes; 99% of the targeted veins were isolated. The mean CF value during ablation was 13 ± 4 g. Intraprocedural early (30 minutes) PV reconnection occurred in 12% PVs, and all PVs were effectively reisolated. One pericardial effusion and five groin hematomas were reported. During a mean follow-up of 12 ± 6 months, 30 (12.9%) (10% paroxysmal AF vs. 18% persistent AF, P = 0.07) patients had an atrial arrhythmias recurrence. In this multicenter registry, RF ablation using a new surround flow catheter, with CF sensor, resulted as feasible, achieving a high rate of isolated PVs. Procedural and fluoroscopy times and success rates were comparable with other techniques with a low complication rate. © 2017 Wiley Periodicals, Inc.

  6. Regulation of exercise blood flow: Role of free radicals. (United States)

    Trinity, Joel D; Broxterman, Ryan M; Richardson, Russell S


    During exercise, oxygen and nutrient rich blood must be delivered to the active skeletal muscle, heart, skin, and brain through the complex and highly regulated integration of central and peripheral hemodynamic factors. Indeed, even minor alterations in blood flow to these organs have profound consequences on exercise capacity by modifying the development of fatigue. Therefore, the fine-tuning of blood flow is critical for optimal physical performance. At the level of the peripheral circulation, blood flow is regulated by a balance between the mechanisms responsible for vasodilation and vasoconstriction. Once thought of as toxic by-products of in vivo chemistry, free radicals are now recognized as important signaling molecules that exert potent vasoactive responses that are dependent upon the underlying balance between oxidation-reduction reactions or redox balance. Under normal healthy conditions with low levels of oxidative stress, free radicals promote vasodilation, which is attenuated with exogenous antioxidant administration. Conversely, with advancing age and disease where background oxidative stress is elevated, an exercise-induced increase in free radicals can further shift the redox balance to a pro-oxidant state, impairing vasodilation and attenuating blood flow. Under these conditions, exogenous antioxidants improve vasodilatory capacity and augment blood flow by restoring an "optimal" redox balance. Interestingly, while the active skeletal muscle, heart, skin, and brain all have unique functions during exercise, the mechanisms by which free radicals contribute to the regulation of blood flow is remarkably preserved across each of these varied target organs. Published by Elsevier Inc.

  7. Whole blood viscosity and cerebral blood flow velocities in obese hypertensive or obese normotensive adolescents. (United States)

    Akcaboy, Meltem; Nazliel, Bijen; Goktas, Tayfun; Kula, Serdar; Celik, Bülent; Buyan, Necla


    Obesity affects all major organ systems and leads to increased morbidity and mortality. Whole blood viscosity is an important independent regulator of cerebral blood flow. The aim of the present study was to evaluate the effect of whole blood viscosity on cerebral artery blood flow velocities using transcranial Doppler ultrasound in pediatric patients with obesity compared to healthy controls and analyze the effect of whole blood viscosity and blood pressure status to the cerebral artery blood flow velocities. Sixty patients with obesity diagnosed according to their body mass index (BMI) percentiles aged 13-18 years old were prospectively enrolled. They were grouped as hypertensive or normotensive according to their ambulatory blood pressure monitoring. Whole blood viscosity and middle cerebral artery velocities by transcranial Doppler ultrasound were studied and compared to 20 healthy same aged controls. Whole blood viscosity values in hypertensive (0.0619±0.0077 poise) and normotensive (0.0607±0.0071 poise) groups were higher than controls (0.0616±0.0064 poise), with no significance. Middle cerebral artery blood flow velocities were higher in the obese hypertensive (73.9±15.0 cm/s) and obese normotensive groups (75.2±13.5 cm/s) than controls (66.4±11.5 cm/s), but with no statistical significance. Physiological changes in blood viscosity and changes in blood pressure did not seem to have any direct effect on cerebral blood flow velocities, the reason might be that the cerebral circulation is capable of adaptively modulating itself to changes to maintain a uniform cerebral blood flow.

  8. [Ocular blood flow and retinal electrogenesis in retinitis pigmentosa]. (United States)

    Kiseleva, T N; Zol'nikova, I V; Demenkova, O N; Ramazanova, K A; Egorova, I V; Rogatina, E V; Rogova, S Yu; Kiseleva, T N; Zol'nikova, I V; Demenkova, O N; Ramazanova, K A; Egorova, I V; Rogatina, E V; Rogova, S Yu


    to investigate correlations between changes in ocular hemodynamics revealed by color Doppler flow mapping (CDFM) and pulsed-wave (PW) Doppler imaging, one the one hand, and electrical activity of the retina, on the other, in patients with early, moderate, and severe retinitis pigmentosa (RP). A total of 20 patients (40 eyes) aged from 16 to 40 years (28.4 ± 8.2 years on average) with retinitis pigmentosa were enrolled. The control group consisted of 20 healthy volunteers of the same age range. All participants underwent full-field electroretinography (ERG), flicker ERG, and macular ERG as well as blood flow assessment in the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (SPCA) by means of CDFM and PW-Doppler. Ocular blood flow in CRA and SPCA appeared disturbed in patients with early RP. In cases of moderate and severe RP, the peak systolic velocity of CRA and SPCA blood flow was significantly decreased. Systolic and end diastolic blood flow velocities in CRA and SPCA has been shown to be directly related to full-field ERG a-wave and b-wave amplitudes, correspondingly, but negatively correlated with their implicit times. The revealed decrease in CRA and SPCA blood flow indices proves retinal and choroidal circulation deficit in patients with advanced RP. As shown, moderate blood flow changes are already present in early RP and progress as retinal photoreceptors and bipolar cells become suppressed, which may be useful for RP diagnosis and monitoring.

  9. Quantitative myocardial blood flow with Rubidium-82 PET

    DEFF Research Database (Denmark)

    Hagemann, Christoffer E; Ghotbi, Adam A; Kjær, Andreas


    Positron emission tomography (PET) allows assessment of myocardial blood flow in absolute terms (ml/min/g). Quantification of myocardial blood flow (MBF) and myocardial flow reserve (MFR) extend the scope of conventional semi-quantitative myocardial perfusion imaging (MPI): e.g. in 1......) identification of the extent of a multivessel coronary artery disease (CAD) burden, 2) patients with balanced 3-vessel CAD, 3) patients with subclinical CAD, and 4) patients with regional flow variance, despite of a high global MFR. A more accurate assessment of the ischemic burden in patients with intermediate...

  10. Doppler ultrasonographic measurement of short-term effects of valsalva maneuver on retrobulbar blood flow. (United States)

    Kimyon, Sabit; Mete, Ahmet; Mete, Alper; Mete, Duçem


    To investigate the effects of Valsalva maneuver (VM) on retrobulbar blood flow parameters in healthy subjects. Participants without any ophthalmologic or systemic pathology were examined in supine position with color and pulsed Doppler imaging for blood flow measurement, via a paraocular approach, in the ophthalmic artery (OA), central retinal artery (CRA), central retinal vein (CRV), nasal posterior ciliary artery (NPCA), and temporal posterior ciliary artery (TPCA), 10 seconds after a 35- to 40-mm Hg expiratory pressure was reached. Peak systolic velocity (PSV), end-diastolic velocity (EDV), pulsatility index (PI), and resistivity index (RI) values were recorded for each artery. PSV and EDV values were recorded for CRV. There were significant differences between resting and VM values of PSV and EDV of CRA, RI of NPCA, and PI, RI, and EDV of TPCA. Resting CRA-EDV, CRV-PSV, and CRV-EDV were positively correlated whereas resting OA-PSV and CRA-PI, and OA-PSV, CRA-PSV, and CRA-EDV during VM, were negatively correlated with age. VM induces a short-term increase in CRA blood flow and a decrease in NPCA and TPCA RI. Additional studies with a longer Doppler recording during VM, in a larger population sample, are required to allow definitive interpretation. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 45:551-555, 2017. © 2017 Wiley Periodicals, Inc.

  11. Noninvasive optical measurement of cerebral blood flow in mice using molecular dynamics analysis of indocyanine green.

    Directory of Open Access Journals (Sweden)

    Taeyun Ku

    Full Text Available In preclinical studies of ischemic brain disorders, it is crucial to measure cerebral blood flow (CBF; however, this requires radiological techniques with heavy instrumentation or invasive procedures. Here, we propose a noninvasive and easy-to-use optical imaging technique for measuring CBF in experimental small animals. Mice were injected with indocyanine green (ICG via tail-vein catheterization. Time-series near-infrared fluorescence signals excited by 760 nm light-emitting diodes were imaged overhead by a charge-coupled device coupled with an 830 nm bandpass-filter. We calculated four CBF parameters including arrival time, rising time and mean transit time of a bolus and blood flow index based on time and intensity information of ICG fluorescence dynamics. CBF maps were generated using the parameters to estimate the status of CBF, and they dominantly represented intracerebral blood flows in mice even in the presence of an intact skull and scalp. We demonstrated that this noninvasive optical imaging technique successfully detected reduced local CBF during middle cerebral artery occlusion. We further showed that the proposed method is sufficiently sensitive to detect the differences between CBF status in mice anesthetized with either isoflurane or ketamine-xylazine, and monitor the dynamic changes in CBF after reperfusion during transient middle cerebral artery occlusion. The near-infrared optical imaging of ICG fluorescence combined with a time-series analysis of the molecular dynamics can be a useful noninvasive tool for preclinical studies of brain ischemia.

  12. Peripheral blood flow control in diabetes mellitus

    DEFF Research Database (Denmark)

    Hilsted, Jannik


    . Whereas the hemodynamic consequences of vascular denervation are well known (causing blood pressure maladaptation to a number of stimuli such as standing, exercise and agonist infusion) (Hilsted 1985), the consequences of disturbances in autoregulation and distensibility remain to be established....

  13. Effleurage massage, muscle blood flow and long-term post-exercise strength recovery. (United States)

    Tiidus, P M; Shoemaker, J K


    Manual massage is commonly assumed to enhance long term muscle recovery from intense exercise, partly due to its ability to speed healing via enhanced muscle blood flow. We tested these assumptions by daily (for four days) massaging the quadriceps muscles of one leg on subjects who had previously completed an intense bout of eccentric quadriceps work with both legs. Immediate post-exercise isometric and dynamic quadriceps peak torque measures had declined to approximately 60-70% of pre-exercise values in both legs. Peak torques for both the massage and control leg tended to slowly return toward pre-exercise values through the subsequent four days (96 hrs). There was no significant difference between the isometric and dynamic peak torques between massage and control legs up to 96 hours post-exercise. Leg blood flow was estimated by determining femoral artery and vein mean blood velocities via pulsed Doppler ultrasound velocimetry. Massage of the quadriceps muscles did not significantly elevate arterial or venous mean blood velocity above resting levels, while light quadriceps muscle contractions did. The perceived level of delayed onset muscle soreness tended to be reduced in the massaged leg 48-96 hours post-exercise. It was concluded that massage was not an effective treatment modality for enhancing long term restoration of post-exercise muscle strength and its use for this purpose in athletic settings should be questioned.

  14. Reduced myocardial blood flow in acute and chronic digitalization. (United States)

    Steiness, E; Bille-Brahe, N E; Hansen, J F; Lomholt, N; Ring-Larsen, H


    The myocardial blood flow was measured by the 133Xenon disappearance curve from the left ventricular wall following an injection of 133Xenon in the left coronary artery in 8 dogs without digoxin pretreatment and in 8 chronically digitalized dogs. The myocardial blood flow was significantly less (30%) in the digitalized dogs than in the dogs without pretreatment. In the digitalized dogs as well as in those without pretreatment an intravenous injection of digoxin resulted in a further significant decrease of the myocardial blood flow of about 20% and a significant increase of the coronary vascular resistance. The reduced myocardial blood flow both during acute and chronic digitalization is beleived to be of clinical importance.

  15. Functional Imaging of Dolphin Brain Metabolism and Blood Flow

    National Research Council Canada - National Science Library

    Ridgway, Sam; Finneran, James; Carder, Don; Keogh, Mandy; Van Bonn, William; Smith, Cynthia; Scadeng, Miriam; Dubowitz, David; Mattrey, Robert; Hoh, Carl


    .... Diazepam has been shown to induce unihemispheric slow waves (USW), therefore we used functional imaging of dolphins with and without diazepam to observe hemispheric differences in brain metabolism and blood flow...

  16. Simulation, Fabrication and Analysis of Silver Based Ascending Sinusoidal Microchannel (ASMC for Implant of Varicose Veins

    Directory of Open Access Journals (Sweden)

    Muhammad Javaid Afzal


    Full Text Available Bioengineered veins can benefit humans needing bypass surgery, dialysis, and now, in the treatment of varicose veins. The implant of this vein in varicose veins has significant advantages over the conventional treatment methods. Deep vein thrombosis (DVT, vein patch repair, pulmonary embolus, and tissue-damaging problems can be solved with this implant. Here, the authors have proposed biomedical microdevices as an alternative for varicose veins. MATLAB and ANSYS Fluent have been used for simulations of blood flow for bioengineered veins. The silver based microchannel has been fabricated by using a micromachining process. The dimensions of the silver substrates are 51 mm, 25 mm, and 1.1 mm, in length, width, and depth respectively. The dimensions of microchannels grooved in the substrates are 0.9 mm in width and depth. The boundary conditions for pressure and velocity were considered, from 1.0 kPa to 1.50 kPa, and 0.02 m/s to 0.07 m/s, respectively. These are the actual values of pressure and velocity in varicose veins. The flow rate of 5.843 (0.1 nL/s and velocity of 5.843 cm/s were determined at Reynolds number 164.88 in experimental testing. The graphs and results from simulations and experiments are in close agreement. These microchannels can be inserted into varicose veins as a replacement to maintain the excellent blood flow in human legs.

  17. Blood flow-vessel interaction in a subclavian aneurysm

    Directory of Open Access Journals (Sweden)

    Alexandru M. MOREGA


    Full Text Available This paper presents a mathematical mode and numerical simulation results of the blood flow-structural interaction, which occurs in a saccular aneurysm emerging out of the left subclavian artery, using computational domains made of by medical images reconstruction. A correlation between the total force per area acting upon the artery walls by the pulsatile blood flow and the rupture probability are also investigated.

  18. Blood flow boosts BMP signaling to keep vessels in shape. (United States)

    Franco, Claudio A; Gerhardt, Holger


    Bone morphogenic proteins (BMPs) and blood flow regulate vascular remodeling and homeostasis. In this issue, Baeyens et al. (2016. J. Cell Biol show that blood flow sensitizes endothelial cells to BMP9 signaling by triggering Alk1/ENG complexing to suppress cell proliferation and to recruit mural cells, thereby establishing endothelial quiescence. © 2016 Franco and Gerhardt.

  19. Blood flow rate measurements with indicator techniques revisited

    DEFF Research Database (Denmark)

    Sejrsen, Per; Bülow, Jens


    In view of the emerging role, disturbances in regional blood flow rate seem to play in the pathogenesis of the metabolic syndrome; we review the concepts of the classical indicator dilution and washout techniques used for determinations of regional blood flow rate. Prerequisites, assumptions......, necessary precautions for the application of these experimental techniques are emphasized. Special attention has been carried out to elucidate the consequence of a choice of indicators having a large distribution volume in the tissues....

  20. Effect of tropicamide on ocular blood flow in the rabbit

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, D.; Michel, P.; Jaanus, S.D.


    Intracardiac injection of 15 microspheres labeled with /sup 85/Sr (strontium) and /sup 141/Ce (cerium) were used to determine ocular blood flow in seven rabbits before and 25 min after bilateral application of tropicamide to the cornea. By using two different isotopes distinguishable under gammaspectrometry, each animal served as its own control. After administration of two drops of 1% tropicamide, no significant difference in blood flow between treated and untreated eyes was observed.

  1. Blood flow and arterial endothelial dysfunction: Mechanisms and implications (United States)

    Barakat, Abdul I.


    The arterial endothelium exquisitely regulates vascular function, and endothelial dysfunction plays a critical role in the development of atherosclerosis. Atherosclerotic lesions develop preferentially at arterial branches and bifurcations where the blood flow is disturbed. Understanding the basis for this observation requires elucidating the effects of blood flow on the endothelial cell (EC) function. The goal of this review is: (1) to describe our current understanding of the relationships between arterial blood flow and atherosclerosis, (2) to present the wide array of flow-induced biological responses in ECs, and (3) to discuss the mechanisms by which ECs sense, transmit, and transduce flow-derived mechanical forces. We conclude by presenting some future perspectives in the highly interdisciplinary field of EC mechanotransduction.

  2. Impaired autoregulation of blood flow in subcutaneous tissue of long-term type 1 (insulin-dependent) diabetic patients with microangiopathy

    DEFF Research Database (Denmark)

    Kastrup, J; Nørgaard, T; Parving, H H


    Autoregulation of blood flow in subcutaneous tissue was studied at the level of the lateral malleolus in eight long-term Type 1 (insulin-dependent) diabetic patients with clinical microangiopathy, eight short-term Type 1 diabetic patients without clinical microangiopathy and seven healthy control...... subjects. Blood flow was measured by the local 133Xenon washout technique. Mean arterial blood pressure was reduced by a maximum of 23 mmHg by elevating the limb above heart level and elevating to a maximum of 70 mmHg by head-up tilt; in the latter position venous pressure was kept constant and low...... by activation of the leg muscle vein pump (heel raising). Mean arterial blood pressure was thus varied between 60 and 160 mmHg. In normal and short-term diabetic subjects blood flow remained within 10% of control values during the changes in arterial blood pressure. In six of the eight Type 1 diabetic patients...

  3. Non-invasive pulmonary blood flow analysis and blood pressure mapping derived from 4D flow MRI (United States)

    Delles, Michael; Rengier, Fabian; Azad, Yoo-Jin; Bodenstedt, Sebastian; von Tengg-Kobligk, Hendrik; Ley, Sebastian; Unterhinninghofen, Roland; Kauczor, Hans-Ulrich; Dillmann, Rüdiger


    In diagnostics and therapy control of cardiovascular diseases, detailed knowledge about the patient-specific behavior of blood flow and pressure can be essential. The only method capable of measuring complete time-resolved three-dimensional vector fields of the blood flow velocities is velocity-encoded magnetic resonance imaging (MRI), often denoted as 4D flow MRI. Furthermore, relative pressure maps can be computed from this data source, as presented by different groups in recent years. Hence, analysis of blood flow and pressure using 4D flow MRI can be a valuable technique in management of cardiovascular diseases. In order to perform these tasks, all necessary steps in the corresponding process chain can be carried out in our in-house developed software framework MEDIFRAME. In this article, we apply MEDIFRAME for a study of hemodynamics in the pulmonary arteries of five healthy volunteers. The study included measuring vector fields of blood flow velocities by phase-contrast MRI and subsequently computing relative blood pressure maps. We visualized blood flow by streamline depictions and computed characteristic values for the left and the right pulmonary artery (LPA and RPA). In all volunteers, we observed a lower amount of blood flow in the LPA compared to the RPA. Furthermore, we visualized blood pressure maps using volume rendering and generated graphs of pressure differences between the LPA, the RPA and the main pulmonary artery. In most volunteers, blood pressure was increased near to the bifurcation and in the proximal LPA, leading to higher average pressure values in the LPA compared to the RPA.

  4. Hepatic and intestinal blood flow following thermal injury

    Energy Technology Data Exchange (ETDEWEB)

    Carter, E.A.; Tompkins, R.G.; Burke, J.F.


    Because cardiac output decreases after burn injuries, investigators have assumed, based upon dye clearance techniques, that hepatic and intestinal blood flow are also decreased following these injuries. Blood flow to the liver, stomach, small intestine, and kidney was determined by the uptake of 201thallium and 125I-labeled fatty acid (para-125I-phenyl-3-methyl pentanoic acid) in a 20% body surface area scald injury that also included plasma volume replacement resuscitation. Uptake of these radioisotopes was determined 15 minutes, 18 hours, and 72 hours after injury. The uptake of the 201thallium and 125I-labeled fatty acid by the gastrointestinal tissues was not statistically different at any of the time periods after comparison of the injured and control (sham-treated) animals. 201Thallium uptake by the kidney was significantly diminished 15 minutes after the burn injury (P less than 0.01). Based on these blood flow measurement techniques, the data suggest that the 20% body surface area scald injury did not alter blood flow to the liver or gastrointestinal tract within the initial 72 hours after the burn injury even though a decrease in renal blood flow was easily detected. These results suggest that the dysfunction of the gastrointestinal system or hepatic system observed after an acute burn injury is not simply the result of hypovolemic shock, which reduces both renal and mesenteric blood flow. These gastrointestinal and hepatic alterations may be related to a factor or factors other than intestinal ischemia.

  5. Tubuloglomerular feedback dynamics and renal blood flow autoregulation in rats

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H; Wagner, A J; Marsh, D J


    To decide whether tubuloglomerular feedback (TGF) can account for renal autoregulation, we tested predictions of a TGF simulation. Broad-band and single-frequency perturbations were applied to arterial pressure; arterial blood pressure, renal blood flow and proximal tubule pressure were measured....... blood flow. We conclude that two components can be detected in the dynamic regulation of renal blood flow, i.e., a slow component that represents TGF and a faster component that most likely represents an intrinsic vascular myogenic mechanism.......To decide whether tubuloglomerular feedback (TGF) can account for renal autoregulation, we tested predictions of a TGF simulation. Broad-band and single-frequency perturbations were applied to arterial pressure; arterial blood pressure, renal blood flow and proximal tubule pressure were measured....... Data were analyzed by linear systems analysis. Broad-band forcings of arterial pressure were also applied to the model to compare experimental results with simulations. With arterial pressure as the input and tubular pressure, renal blood flow, or renal vascular resistance as outputs, the model...

  6. Computational model on pulsatile flow of blood through a tapered ...

    Indian Academy of Sciences (India)

    An unsteady two-fluid model of blood flow through a tapered arterial stenosis with variable viscosity in the presence of variable magnetic field has been analysed in the present paper. In this article, blood in the core region is assumed to obey the law of Jeffrey fluid and plasma in the peripheral layer is assumed to be ...

  7. Femoral Blood Flow and Cardiac Output During Blood Flow Restricted Leg Press Exercise (United States)

    Everett, M. E.; Hackney, K.; Ploutz-Snyder, L.


    Low load blood flow restricted resistance exercise (LBFR) causes muscle hypertrophy that may be stimulated by the local ischemic environment created by the cuff pressure. However, local blood flow (BF) during such exercise is not well understood. PURPOSE: To characterize femoral artery BF and cardiac output (CO) during leg press exercise (LP) performed at a high load (HL) and low load (LL) with different levels of cuff pressure. METHODS: Eleven subjects (men/women 4/7, age 31.4+/-12.8 y, weight 68.9+/-13.2 kg, mean+/-SD) performed 3 sets of supine left LP to fatigue with 90 s of rest in 4 conditions: HL (%1-RM/cuff pressure: 80%/0); LL (20%/0); LBFR(sub DBP) (20%/1.3 x diastolic blood pressure, BP); LBFR(sub SBP) (20%/1.3 x supine systolic BP). The cuff remained inflated throughout the LBFR exercise sessions. Artery diameter, velocity time integral (VTI), and stroke volume (SV) were measured using Doppler ultrasound at rest and immediately after each set of exercise. Heart rate (HR) was monitored using a 3-lead ECG. BF was calculated as VTI x vessel cross-sectional area. CO was calculated as HR x SV. The data obtained after each set of exercise were averaged and used for analyses. Multi-level modeling was used to determine the effect of exercise condition on dependent variables. Statistical significance was set a priori at p LL (9.92+/-0.82 cm3) > LBFR(sub dBP)(6.47+/-0.79 cm3) > LBFR(sub SBP) (3.51+/-0.59 cm3). Blunted exercise induced increases occurred in HR, SV, and CO after LBFR compared to HL and LL. HR increased 45% after HL and LL and 28% after LBFR (p<0.05), but SV increased (p<0.05) only after HL. Consequently, the increase (p<0.05) in CO was greater in HL and LL (approximately 3 L/min) than in LBFR (approximately 1 L/min). CONCLUSION: BF during LBFR(sub SBP) was 1/3 of that observed in LL, which supports the hypothesis that local ischemia stimulates the LBFR hypertrophic response. As the cuff did not compress the artery, the ischemia may have occurred

  8. Pulsed cavitational therapy using high-frequency ultrasound for the treatment of deep vein thrombosis in an in vitro model of human blood clot (United States)

    Goudot, G.; Mirault, T.; Arnal, B.; Boisson-Vidal, C.; Le Bonniec, B.; Gaussem, P.; Galloula, A.; Tanter, M.; Messas, E.; Pernot, M.


    Post-thrombotic syndrome, a frequent complication of deep venous thrombosis, can be reduced with early vein recanalization. Pulsed cavitational therapy (PCT) using ultrasound is a recent non-invasive approach. We propose to test the efficacy and safety of high-frequency focused PCT for drug-free thrombolysis (thrombotripsy) in a realistic in vitro model of venous thrombosis. To reproduce venous thrombosis conditions, human whole blood was allowed to clot by stasis in silicone tubes (6 mm internal diameter) at a 30 cm H2O pressure, maintained during the whole experiment. We engineered an ultrasound device composed of dual 2.25 MHz transducers centered around a 6 MHz imaging probe. A therapeutic focus was generated at a 3.2 cm depth from the probe. Thrombotripsy was performed by longitudinally scanning the thrombus at three different speeds: 1 mm s‑1 (n  =  6) 2 mm s‑1 (n  =  6) 3 mm s‑1 (n  =  12). Restored outflow was measured every three passages. Filters were placed to evaluate the debris size. Twenty-four occlusive thrombi, of 2.5 cm mean length and 4.4 kPa mean stiffness, were studied. Flow restoration was systematically obtained by nine subsequent passages (4.5 min maximum). By varying the device’s speed, we found an optimal speed of 1 mm s‑1 to be efficient for effective recanalization with 90 s (three passages). Within 90 s, flow restoration was of 80, 62 and 74% at respectively 1, 2 and 3 mm s‑1. For all groups, cavitation cloud drilled a 1.7 mm mean diameter channel throughout the clot. Debris analysis showed 92% of debris    200 µm.

  9. Fast Blood Vector Velocity Imaging using ultrasound: In-vivo examples of complex blood flow in the vascular system

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Udesen, Jesper; Gran, Fredrik


    speckle tracking between segments in consecutive speckle images. The flow patterns of six bifurcations and two veins were investigated in-vivo. It was shown: 1) that a stable vortex in the carotid bulb was present opposed to other examined bifurcations, 2) that retrograde flow was present...

  10. Blood flow and clearance in tendons. Studies with dogs. (United States)

    Hooper, G; Davies, R; Tothill, P


    Blood flow in intact tendons in dogs was measured using 57Co-labelled microspheres and compared with the simultaneous clearance of a diffusible radionuclide, 85Sr, by the same tendons. Clearance was significantly greater than flow in all tendons, indicating that diffusion from surrounding tissues may be important in the nutrition of normal tendons.

  11. Methods for measurement of cerebral blood flow in man

    DEFF Research Database (Denmark)

    Lassen, N A


    A survey of the currently available methods for the measurement of cerebral blood flow in man is given. Many of the clinically important brain diseases such as tumors, stroke, brain trauma or epilepsy entail focal or regional flow alterations. Therefore a special emphasis is placed on methods all...

  12. Building a 3D Virtual Liver: Methods for Simulating Blood Flow and Hepatic Clearance on 3D Structures. (United States)

    White, Diana; Coombe, Dennis; Rezania, Vahid; Tuszynski, Jack


    In this paper, we develop a spatio-temporal modeling approach to describe blood and drug flow, as well as drug uptake and elimination, on an approximation of the liver. Extending on previously developed computational approaches, we generate an approximation of a liver, which consists of a portal and hepatic vein vasculature structure, embedded in the surrounding liver tissue. The vasculature is generated via constrained constructive optimization, and then converted to a spatial grid of a selected grid size. Estimates for surrounding upscaled lobule tissue properties are then presented appropriate to the same grid size. Simulation of fluid flow and drug metabolism (hepatic clearance) are completed using discretized forms of the relevant convective-diffusive-reactive partial differential equations for these processes. This results in a single stage, uniformly consistent method to simulate equations for blood and drug flow, as well as drug metabolism, on a 3D structure representative of a liver.

  13. Glucagon-like peptide-2 (GLP-2) increases small intestinal blood flow and mucosal growth in ruminating calves

    DEFF Research Database (Denmark)

    Taylor-Edwards, C C; Burrin, D G; Holst, Jens Juul


    Glucagon-like peptide-2 (GLP-2) increases small intestinal mass and blood flow in nonruminants but its effect in ruminants is unknown. Eight Holstein calves with an ultrasonic flow probe around the superior mesenteric artery and catheters in the carotid artery and mesenteric vein were paired by age...... of BSA or 1,000 pmol of GLP-2/kg of body weight per h), and recovery (saline infusion). On d 11, calves were killed 2h after injection of 5-bromo-2'-deoxyuridine (BrdU). Gastrointestinal tissues were weighed and epithelial samples were obtained to determine villus height, crypt depth, and BrdU staining....... Infusion of GLP-2 increased superior mesenteric artery blood flow to 175% of baseline on d 0 but to only 137% of baseline after chronic treatment. Compared with that of the control, GLP-2 increased small intestinal mass by 24% by increasing epithelial mass in the jejunum and ileum. Additionally, GLP-2...

  14. Ultrasonic Enrichment of Flowing Blood Cells in Capillars: Influence of the Flow Rate (United States)

    Carreras, Pilar; Gonzalez, Itziar; Ahumada, Oscar

    Red blood cells subjected to standing waves collect at the pressure nodes during their flow motion. Blood is a non-newtonian fluid whose density and other properties are defined by its flow velocity. Their drift motion is governed by the radiation force together with hydrodynamic conditions. This work presents a study of the blood cell enrichment performed in a rectangular capillar at f=1 MHz as a function of their flow motion. The cells collect along the central axis of the capillary in very few seconds, with a clearance in other lateral areas. Optimal flow rates below 100uL/min were found in the experiments.


    DEFF Research Database (Denmark)

    Pavlov, A.N.; Pavlova, O.N.; Mosekilde, Erik


    The purpose of this study is to demonstrate the possibility of revealing new characteristic features of renal blood flow autoregulation in healthy and pathological states through the application of discrete wavelet transforms to experimental time series for normotensive and hypertensive rats....... A reduction in the variability of the wavelet coefficients in hypertension is observed at both the microscopic level of the blood flow in efferent arterioles of individual nephrons and at the macroscopic level of the blood pressure in the main arteries. The reduction is manifest in both of the main frequency...

  16. Vasodilator interactions in skeletal muscle blood flow regulation

    DEFF Research Database (Denmark)

    Hellsten, Ylva; Nyberg, Michael Permin; Jensen, Lasse Gliemann


    During exercise, oxygen delivery to skeletal muscle is elevated to meet the increased oxygen demand. The increase in blood flow to skeletal muscle is achieved by vasodilators formed locally in the muscle tissue, either on the intraluminal or the extraluminal side of the blood vessels. A number...... that this remaining hyperemia may be explained by cAMP and cGMP independent smooth muscle relaxation, such as effects of endothelial derived hyperpolarization factors (EDHFs) or through metabolic modulation of sympathetic effects. The nature and role of EDHF as well as potential novel mechanisms in muscle blood flow...

  17. Mesenteric stenosis, collaterals, and compensatory blood flow

    NARCIS (Netherlands)

    van Petersen, Andre S.; Kolkman, Jeroen J.; Meerwaldt, Robbert; Huisman, Ad B.; van der Palen, Jacobus Adrianus Maria; Zeebregts, Clark J.; Geelkerken, Robert H.


    Background The mesenteric circulation has an extensive collateral network. Therefore, stenosis in one or more mesenteric arteries does not necessarily lead to symptoms. The objective of this study was to determine the effect of collateral flow on celiac artery (CA) and superior mesenteric artery

  18. Mesenteric stenosis, collaterals, and compensatory blood flow

    NARCIS (Netherlands)

    van Petersen, Andre S.; Kolkman, Jeroen J.; Meerwaldt, Robbert; Huisman, Ad B.; van der Palen, Job; Zeebregts, Clark J.; Geelkerken, Robert H.

    Background: The mesenteric circulation has an extensive collateral network. Therefore, stenosis in one or more mesenteric arteries does not necessarily lead to symptoms. The objective of this study was to determine the effect of collateral flow on celiac artery (CA) and superior mesenteric artery

  19. Estimating blood flow velocity in angiographic image data (United States)

    Hentschke, Clemens M.; Serowy, Steffen; Janiga, Gábor; Rose, Georg; Tönnies, Klaus D.


    We propose a system to estimate blood flow velocity in angiographic image data for patient-specific blood flow simulations. Angiographies are acquired routinely for diagnosis and before treatment of vascular diseases. Projective blood flow is measured in digital subtraction X-ray angiography (2D-DSA) images by tracking contrast agent propagation. Spatial information is added by re-projecting 2D centerline pixels to the reconstructed 3D X-ray rotation angiography (3D-RA) data of the same subject. Ambiguities caused by occluding vessels from the virtual viewpoint of the acquired 2D-DSA image are resolved by a graph-based approach. The blood flow velocity can be used as boundary condition for exact blood flow simulations that can help physicians to understand hemodynamics of the vasculature. Our focus is to analyze cerebral angiographic data. We performed several experiments with phantom and patient data that proved the accuracy and the functionality of our method. We evaluated experimentally the projective flow estimation method and the re-projection method. We measured mean deviations to the ground truth between 11 % and 15.7 % for phantom data. We also showed the ability of our method to produce plausible results with patient-data.

  20. Geometric analysis and blood flow simulation of basilar artery. (United States)

    Lee, Sang Hyuk; Hur, Nahmkeon; Jeong, Seul-Ki


    The aim of this study was to find a region of low wall shear stress (WSS) in a basilar artery using 3-dimensional (3D) geometric analysis and blood flow simulation. A 61-year-old patient who underwent follow-up time-of-flight magnetic resonance angiography (TOF-MRA) of the brain was recruited as the subject of the present study. In the basilar artery, the angle of the directional vector was calculated for the region of low WSS. The subject's 3D arterial geometry and blood flow velocity from a transcranial Doppler examination were used for a blood flow simulation study. The regions of low WSS identified by both geometric analysis and blood flow simulation were compared, and these methods were repeated for the basilar arteries of various geometries from other patients. Two distinct arterial angulations along the basilar artery were identified: lateral and anterior angulations on the anteroposterior and lateral TOF-MR views, respectively. A low WSS region was observed in the distal portion along the inner curvatures of both angulations in the basilar artery. The directional vectors of the region of low WSS calculated by geometric analysis and blood flow simulation were very similar (correlation coefficient= 0.996, p flow simulation of the basilar artery identified lateral and anterior angulations which determined the low WSS region in the distal portion along the inner curvatures of the angulations.

  1. Viscoelastic capillary flow: the case of whole blood

    Directory of Open Access Journals (Sweden)

    David Rabaud


    Full Text Available The dynamics of spontaneous capillary flow of Newtonian fluids is well-known and can be predicted by the Lucas-Washburn-Rideal (LWR law. However a wide variety of viscoelastic fluids such as alginate, xanthan and blood, does not exhibit the same Newtonian behavior.In this work we consider the Herschel-Bulkley (HB rheological model and Navier-Stokes equation to derive a generic expression that predicts the capillary flow of non-Newtonian fluids. The Herschel-Bulkley rheological model encompasses a wide variety of fluids, including the Power-law fluids (also called Ostwald fluids, the Bingham fluids and the Newtonian fluids. It will be shown that the proposed equation reduces to the Lucas-Washburn-Rideal law for Newtonian fluids and to the Weissenberg-Rabinowitsch-Mooney (WRM law for power-law fluids. Although HB model cannot reduce to Casson’s law, which is often used to model whole blood rheology, HB model can fit the whole blood rheology with the same accuracy.Our generalized expression for the capillary flow of non-Newtonian fluid was used to accurately fit capillary flow of whole blood. The capillary filling of a cylindrical microchannel by whole blood was monitored. The blood first exhibited a Newtonian behavior, then after 7 cm low shear stress and rouleaux formation made LWR fails to fit the data: the blood could not be considered as Newtonian anymore. This non-Newtonian behavior was successfully fit by the proposed equation.

  2. Nephron blood flow dynamics measured by laser speckle contrast imaging

    DEFF Research Database (Denmark)

    von Holstein-Rathlou, Niels-Henrik; Sosnovtseva, Olga V; Pavlov, Alexey N


    Tubuloglomerular feedback (TGF) has an important role in autoregulation of renal blood flow and glomerular filtration rate (GFR). Because of the characteristics of signal transmission in the feedback loop, the TGF undergoes self-sustained oscillations in single-nephron blood flow, GFR, and tubular...... pressure and flow. Nephrons interact by exchanging electrical signals conducted electrotonically through cells of the vascular wall, leading to synchronization of the TGF-mediated oscillations. Experimental studies of these interactions have been limited to observations on two or at most three nephrons...... simultaneously. The interacting nephron fields are likely to be more extensive. We have turned to laser speckle contrast imaging to measure the blood flow dynamics of 50-100 nephrons simultaneously on the renal surface of anesthetized rats. We report the application of this method and describe analytic...

  3. Blood flow and stem cells in vascular disease. (United States)

    Zhang, Cheng; Zeng, Lingfang; Emanueli, Costanza; Xu, Qingbo


    It is well known that the altered blood flow is related to vascular diseases, including atherosclerosis, restenosis, and arteriosclerosis, which preferentially located at areas with the disturbed blood flow, suggesting that altered biomechanical stress may exert their effect on the vascular disease. Recent evidence indicated the presence of abundant stem/progenitor cells in the vessel wall, in which laminar shear stress can stimulate these cells to differentiate towards endothelial lineage, while cyclic strain results in smooth muscle differentiation. In line with this, it was evidenced that altered biomechanical stress in stented vessels may lead to 'wrong' direction of vascular stem cell differentiation resulting in restenosis. However, the underlying mechanisms are not well understood. In this article, we will give an overview of the effect of the local flow pattern on stem/progenitor cell differentiation and the possible mechanism on how the blood flow influences stem cell behaviours in the development of vascular diseases.

  4. Intrinsic regulation of blood flow in adipose tissue

    DEFF Research Database (Denmark)

    Henriksen, O; Nielsen, Steen Levin; Paaske, W


    Previous studies on intact human subcutaneous tissue have shown, that blood flow remains constant during minor changes in perfusion pressure. This so-called autoregulatory response has not been demonstrable in isolated preparations of adipose tissue. In the present study on isolated, denervated...... subcutaneous tissue in female rabbits only 2 of 12 expts. revealed an autoregulatory response during reduction in arterial perfusion pressure. Effluent blood flow from the tissue in the control state was 15.5 ml/100 g-min (S.D. 6.4, n = 12) corresponding to slight vasodilatation of the exposed tissue....... Following total ischemia all experiments showed a period with reactive hyperemia, and both duration of hyperemia and excess flow was related to the duration of the ischemia. This response therefore seems more resistant to the experimental procedure, while autoregulation of blood flow to lowered pressure...

  5. Pulsatile blood flow, shear force, energy dissipation and Murray's Law

    Directory of Open Access Journals (Sweden)

    Bengtsson Hans-Uno


    Full Text Available Abstract Background Murray's Law states that, when a parent blood vessel branches into daughter vessels, the cube of the radius of the parent vessel is equal to the sum of the cubes of the radii of daughter blood vessels. Murray derived this law by defining a cost function that is the sum of the energy cost of the blood in a vessel and the energy cost of pumping blood through the vessel. The cost is minimized when vessel radii are consistent with Murray's Law. This law has also been derived from the hypothesis that the shear force of moving blood on the inner walls of vessels is constant throughout the vascular system. However, this derivation, like Murray's earlier derivation, is based on the assumption of constant blood flow. Methods To determine the implications of the constant shear force hypothesis and to extend Murray's energy cost minimization to the pulsatile arterial system, a model of pulsatile flow in an elastic tube is analyzed. A new and exact solution for flow velocity, blood flow rate and shear force is derived. Results For medium and small arteries with pulsatile flow, Murray's energy minimization leads to Murray's Law. Furthermore, the hypothesis that the maximum shear force during the cycle of pulsatile flow is constant throughout the arterial system implies that Murray's Law is approximately true. The approximation is good for all but the largest vessels (aorta and its major branches of the arterial system. Conclusion A cellular mechanism that senses shear force at the inner wall of a blood vessel and triggers remodeling that increases the circumference of the wall when a shear force threshold is exceeded would result in the observed scaling of vessel radii described by Murray's Law.

  6. Partitioning of red blood cell aggregates in bifurcating microscale flows (United States)

    Kaliviotis, E.; Sherwood, J. M.; Balabani, S.


    Microvascular flows are often considered to be free of red blood cell aggregates, however, recent studies have demonstrated that aggregates are present throughout the microvasculature, affecting cell distribution and blood perfusion. This work reports on the spatial distribution of red blood cell aggregates in a T-shaped bifurcation on the scale of a large microvessel. Non-aggregating and aggregating human red blood cell suspensions were studied for a range of flow splits in the daughter branches of the bifurcation. Aggregate sizes were determined using image processing. The mean aggregate size was marginally increased in the daughter branches for a range of flow rates, mainly due to the lower shear conditions and the close cell and aggregate proximity therein. A counterintuitive decrease in the mean aggregate size was apparent in the lower flow rate branches. This was attributed to the existence of regions depleted by aggregates of certain sizes in the parent branch, and to the change in the exact flow split location in the T-junction with flow ratio. The findings of the present investigation may have significant implications for microvascular flows and may help explain why the effects of physiological RBC aggregation are not deleterious in terms of in vivo vascular resistance.

  7. Coded ultrasound for blood flow estimation using subband processing

    DEFF Research Database (Denmark)

    Gran, F.; Udesen, J.; Jensen, J.A.


    This paper investigates the use of coded excitation for blood flow estimation in medical ultrasound. Traditional autocorrelation estimators use narrow-band excitation signals to provide sufficient signal-to-noise-ratio (SNR) and velocity estimation performance. In this paper, broadband coded...... the excitation signal is broadband and has good spatial resolution after pulse compression. This means that time can be saved by using the same data for B-mode imaging and blood flow estimation. Two different coding schemes are used in this paper, Barker codes and Golay codes. The performance of the codes...... for velocity estimation is compared with a conventional approach transmitting a narrow-band pulse. The study was carried out using an experimental ultrasound scanner and a commercial linear array 7 MHz transducer. A circulating flow rig was scanned with a beam-to-flow angle of 60 degrees. The flow in the rig...

  8. Coded Ultrasound for Blood Flow Estimation Using Subband Processing

    DEFF Research Database (Denmark)

    Gran, Fredrik; Udesen, Jesper; Nielsen, Michael Bachamnn


    This paper investigates the use of coded excitation for blood flow estimation in medical ultrasound. Traditional autocorrelation estimators use narrow-band excitation signals to provide sufficient signal-to-noise-ratio (SNR) and velocity estimation performance. In this paper, broadband coded...... the excitation signal is broadband and has good spatial resolution after pulse compression. This means that time can be saved by using the same data for B-mode imaging and blood flow estimation. Two different coding schemes are used in this paper, Barker codes and Golay codes. The performance of the codes...... for velocity estimation is compared with a conventional approach transmitting a narrow-band pulse. The study was carried out using an experimental ultrasound scanner and a commercial linear array 7 MHz transducer. A circulating flow rig was scanned with a beam-to-flow angle of 60°. The flow in the rig...

  9. Intermittent calf and foot compression increases lower extremity blood flow. (United States)

    Eze, A R; Comerota, A J; Cisek, P L; Holland, B S; Kerr, R P; Veeramasuneni, R; Comerota, A J


    Although foot compression increases foot skin perfusion and calf compression increases popliteal artery blood flow, these compression techniques have not been evaluated in combination. The purpose of this study was to evaluate whether calf and foot compression applied separately and simultaneously increase popliteal artery blood flow and/or foot skin perfusion, and to assess the relative merits of compression in patients with superficial femoral artery occlusion. Twenty-two legs from 12 normal volunteers with ankle/brachial indices (ABIs) > 0.96, and 10 legs from 7 claudicator patients with angiographically documented superficial femoral artery (SFA) occlusion and patent popliteal arteries with ABIs pressure pump (Art-Assist-AA 1000; ACI Medical Inc., San Marcos, California) were applied to the subject in the sitting position. Skin blood flow of the great toe was measured with a laser doppler (Laserflo model BPM 403A; TSI Inc., St. Paul, Minnesota), and popliteal artery blood flow was measured using duplex ultrasonography (ATL-Ultramark 9; Advanced Tech Laboratory, Bothell, Washington). Foot and calf compression was applied separately and simultaneously at 120 mm Hg pressure, with a 10-second inflation and 20-second deflation cycle. Popliteal artery blood flow and foot skin perfusion were recorded and the mean of 6 cycles calculated. Precompression popliteal artery blood flow (mL/min) for volunteers was 38.86 +/- 3.94, and for patients was 86.30 +/- 14.55 (P = 0.001). Precompression foot skin perfusion (mL/min/ 100/g tissue) for volunteers was 1.67 +/- 0.29, and for patients was 4.00 +/- 0.92 (P = 0.01). With the application of calf, foot, and simultaneous calf and foot compression, the popliteal artery blood flow increased in volunteers by 124%, 54%, and 173%, respectively, and in patients by 76%, 13%, and 50%. Foot skin perfusion increased in volunteers by 260%, 500%, and 328%, respectively, and in patients by 116%, 246%, and 188%. Relative increases in popliteal

  10. Ethanol embolotherapy of high-flow auricular arteriovenous malformations with electrolytically detachable coil-assisted dominant outflow vein occlusion. (United States)

    Wang, D; Su, L; Han, Y; Fan, X


    High-flow arteriovenous malformations (AVMs) with a dominant outflow vein (DOV) remain difficult for ethanol embolotherapy, but improved technology and experience of detachable coils allows for the treatment of some of these AVMs with satisfactory results. A single-center experience and evaluation of technical and clinical safety, and effectiveness of electrolytically detachable coil (EDC)-assisted DOV occlusion for ethanol embolization of high-flow auricular AVMs, which has some advantages over conventional coils because of its controlled deployment, reposition, and removal is reported. From November 2010 to June 2013, 40 consecutive patients with auricular AVMs underwent staged ethanol embolizations, of which nine patients' auricular AVMs with a DOV who had undergone ethanol embolization of high-flow auricular AVMs in combination with EDCs-assisted DOV occlusion were retrospectively evaluated. Clinical follow-up (range, 5-29 months; mean, 15.1 months) was completed in all patients, and results from imaging follow-up (range, 7-25 months; mean, 14.7 months) were available from the last treatment session in six patients. Therapeutic outcomes were determined by evaluating the clinical outcome of symptoms and signs, as well as the degree of devascularization at follow-up arteriography. Twenty-eight ethanol embolizations and nine EDC-assisted DOV occlusions were performed in nine patients. Seventeen EDCs were used in nine patients. Five (55.6%) of the nine patients were cured, and four (44.4%) had partial palliation. One minor complication occurred in one of the nine patients. Transient hemoglobinuria occurred in six of nine patients in a total nine of the 28 procedures. There were no major complications. Ethanol embolization has the potential for cure in the management of high-flow auricular AVMs with the aid of occlusion DOV by EDCs with acceptable risk of minor and major complications. Copyright © 2014 European Society for Vascular Surgery. Published by Elsevier

  11. Velocity Estimation of the Main Portal Vein with Transverse Oscillation

    DEFF Research Database (Denmark)

    Brandt, Andreas Hjelm; Hansen, Kristoffer Lindskov; Nielsen, Michael Bachmann


    This study evaluates if Transverse Oscillation (TO) can provide reliable and accurate peak velocity estimates of blood flow the main portal vein. TO was evaluated against the recommended and most widely used technique for portal flow estimation, Spectral Doppler Ultrasound (SDU). The main portal...... and subcostal were significantly different (intercostal mean SDU=0.202m/s, subcostal mean SDU=0.320m/s, pindicating a large beam-to-flow angle variability in the portal vein. This can affect the peak velocity estimation...

  12. Influences of Hydraulic Fracturing on Fluid Flow and Mineralization at the Vein-Type Tungsten Deposits in Southern China

    Directory of Open Access Journals (Sweden)

    Xiangchong Liu


    Full Text Available Wolframite is the main ore mineral at the vein-type tungsten deposits in the Nanling Range, which is a world-class tungsten province. It is disputed how wolframite is precipitated at these deposits and no one has yet studied the links of the mechanical processes to fluid flow and mineralization. Finite element-based numerical experiments are used to investigate the influences of a hydraulic fracturing process on fluid flow and solubility of CO2 and quartz. The fluids are aqueous NaCl solutions and fluid pressure is the only variable controlling solubility of CO2 and quartz in the numerical experiments. Significant fluctuations of fluid pressure and high-velocity hydrothermal pulse are found once rock is fractured by high-pressure fluids. The fluid pressure drop induced by hydraulic fracturing could cause a 9% decrease of quartz solubility. This amount of quartz deposition may not cause a significant decrease in rock permeability. The fluid pressure decrease after hydraulic fracturing also reduces solubility of CO2 by 36% and increases pH. Because an increase in pH would cause a major decrease in solubility of tungsten, the fluid pressure drop accompanying a hydraulic fracturing process facilitates wolframite precipitation. Our numerical experiments provide insight into the mechanisms precipitating wolframite at the tungsten deposits in the Nanling Range as well as other metals whose solubility is strongly dependent on pH.

  13. One dimensional blood flow in a planetocentric orbit (United States)

    Haranas, Ioannis; Gkigkitzis, Ioannis


    All life on earth is accustomed to the presence of gravity. When gravity is altered, biological processes can go awry. It is of great importance to ensure safety during a spaceflight. Long term exposure to microgravity can trigger detrimental physiological responses in the human body. Fluid redistribution coupled with fluid loss is one of the effects. In particular, in microgravity blood volume is shifted towards the thorax and head. Sympathetic nervous system-induced vasoconstriction is needed to maintain arterial pressure, while venoconstriction limits venous pooling of blood prevents further reductions in venous return of blood to the heart. In this paper, we modify an existing one dimensional blood flow model with the inclusion of the hydrostatic pressure gradient that further depends on the gravitational field modified by the oblateness and rotation of the Earth. We find that the velocity of the blood flow VB is inversely proportional to the blood specific volume d, also proportional to the oblateness harmonic coefficient J2, the angular velocity of the Earth ωE, and finally proportional to an arbitrary constant c. For c = -0.39073 and ξH = -0.5 mmHg, all orbits result to less blood flow velocities than that calculated on the surface of the Earth. From all considered orbits, elliptical polar orbit of eccentricity e = 0.2 exhibit the largest flow velocity VB = 1.031 m/s, followed by the orbits of inclination i = 45°and 0°. The Earth's oblateness and its rotation contribute a 0.7% difference to the blood flow velocity.

  14. Effects of posture on limb blood flow in late pregnancy. (United States)

    Drummond, G B; Scott, S E; Lees, M M; Scott, D B


    Arm and leg blood flow was measured in 40 patients in late pregnancy in the supine and left lateral positions, and the changes were contrasted with changes found in 15 patients investigated in the early puerperium. A significant reduction in leg flow occurred in the pregnant subjects when the supine position was assumed. A further 30 patients in late pregnancy had leg flow measured in the following positions: left lateral, supine, right lateral, and the two mid-positions. Leg flow significantly increased on moving from the supine to all other positions except the right intermediate position, indicating that a leftward tilt is more effective in preventing caval compression.

  15. Magnetic resonance imaging and measurement of blood flow.


    McDonnell, C H; Herfkens, R J; Norbash, A M; Rubin, G D


    Blood flow can be shown as a negative image with magnetic resonance spin-echo techniques or as a positive image with gradient-echo techniques. Phase contrast refers to techniques where structures can be seen because of flow-induced phase shifts. These techniques can show the presence (slow flow) and also the direction of flow. Gradient-echo techniques--including phase-contrast versions--can be used with cardiac synchronization to obtain multiple images during the cardiac cycle. These images c...

  16. The Effect of Lipemia on Peripheral Blood Flow (United States)

    Zsotér, Thomas; Fam, Wadie M.; McGregor, Maurice


    The effect of lipemia on peripheral blood flow was studied in patients with and without peripheral vascular disease. Blood flow was measured by venous occlusion plethysmography in the calf and/or finger four to six hours after a fatty meal and after intravenous heparin. The abolition of postprandial lipemia by heparin was determined by measuring the plasma lactescence. Heparin resulted in no change in finger flow of either group or in calf flow in the control group. In nine out of 10 patients with occlusive vascular disease of the legs, it resulted in a small but significant increase of calf blood flow. No such alteration was found when heparin was given following a non-fatty meal. In 12 patients with intermittent claudication the clearing of postprandial lipemia by heparin caused prolongation of claudication time, as measured by the appearance of pain on treadmill exercise. It is concluded that, in some cases, postprandial lipemia is associated with a decrease in blood flow in a limb which is already the site of occlusive vascular disease. PMID:14146862

  17. Alterations in Cerebral Blood Flow after Resuscitation from Cardiac Arrest

    Directory of Open Access Journals (Sweden)

    Bistra Iordanova


    Full Text Available Greater than 50% of patients successfully resuscitated from cardiac arrest have evidence of neurological disability. Numerous studies in children and adults, as well as in animal models have demonstrated that cerebral blood flow (CBF is impaired after cardiac arrest. Stages of cerebral perfusion post-resuscitation include early hyperemia, followed by hypoperfusion, and finally either resolution of normal blood flow or protracted hyperemia. At the level of the microcirculation the blood flow is heterogeneous, with areas of no flow, low flow, and increased flow. CBF directed therapies in animal models of cardiac arrest improved neurological outcome, and therefore, the alterations in CBF after cardiac arrest likely contribute to the development of hypoxic ischemic encephalopathy. Current intensive care after cardiac arrest is centered upon maintaining systemic oxygenation, normal blood pressure values for age, maintaining general homeostasis, and avoiding hyperthermia. Assessment of CBF and oxygenation is not routinely performed after cardiac arrest. Currently available and underutilized techniques to assess cerebral perfusion include transcranial doppler, near-infrared spectroscopy, and arterial spin labeling magnetic resonance imaging. Limited clinical studies established the role of CBF and oxygenation monitoring in prognostication after cardiac arrest and few studies suggest that guiding critical care post-resuscitation to mean arterial pressures above the minimal autoregulatory range might improve outcome. Important knowledge gaps thus remain in cerebral monitoring and CBF and oxygen goal-directed therapies post-resuscitation from cardiac arrest.

  18. Technetium-99m red blood cell venography in patients with clinically suspected deep vein thrombosis: a prospective study

    Energy Technology Data Exchange (ETDEWEB)

    Leclerc, J.R.; Wolfson, C.; Arzoumanian, A.; Blake, G.P.; Rosenthall, L.


    We have compared technetium-99m (99mTc) red blood cell (RBC) venography to serial impedance plethysmography (IPG) in 110 consecutive patients with a first episode of clinically suspected deep vein thrombosis (DVT). IPG was performed at Day 0 and, if abnormal, contrast venography was also performed to rule out a falsely positive result. Patients with an initially normal IPG had the test repeated at Days 1, 3, 5 to 7, and 10 to 14. Contrast venography was not performed and anticoagulant treatment was withheld in all patients who remained normal during repeated IPG testing. Technetium-99m RBC venography was performed at Day 0 in patients with an initially abnormal IPG and during the period of serial IPG testing in those with an initially normal IPG. The sensitivity of (99mTc)RBC venography for proximal DVT was 0.68, with 95% confidence limits (CL) from 0.48 to 0.89. Specificity was 0.88 (95% CL from 0.81 to 0.95). When the findings of (99mTc)RBC venography for the entire lower extremity were compared to the reference method, the sensitivity increased to 0.90 (95% CL from 0.82 to 0.97) but the specificity decreased to 0.56 (95% CL from 0.51 to 0.62). Technetium-99m RBC venography is a sensitive but less specific method for detecting DVT of the entire lower extremity. An abnormal (99mTc)RBC venogram, particularly in the calf region, should always be confirmed by another diagnostic method.

  19. A Mixed Approach for Modeling Blood Flow in Brain Microcirculation (United States)

    Lorthois, Sylvie; Peyrounette, Myriam; Davit, Yohan; Quintard, Michel; Groupe d'Etude sur les Milieux Poreux Team


    Consistent with its distribution and exchange functions, the vascular system of the human brain cortex is a superposition of two components. At small-scale, a homogeneous and space-filling mesh-like capillary network. At large scale, quasi-fractal branched veins and arteries. From a modeling perspective, this is the superposition of: (a) a continuum model resulting from the homogenization of slow transport in the small-scale capillary network; and (b) a discrete network approach describing fast transport in the arteries and veins, which cannot be homogenized because of their fractal nature. This problematic is analogous to fast conducting wells embedded in a reservoir rock in petroleum engineering. An efficient method to reduce the computational cost is to use relatively large grid blocks for the continuum model. This makes it difficult to accurately couple both components. We solve this issue by adapting the ``well model'' concept used in petroleum engineering to brain specific 3D situations. We obtain a unique linear system describing the discrete network, the continuum and the well model. Results are presented for realistic arterial and venous geometries. The mixed approach is compared with full network models including various idealized capillary networks of known permeability. ERC BrainMicroFlow GA615102.

  20. Involvement of calcitonin gene-related peptide in migraine: regional cerebral blood flow and blood flow velocity in migraine patients

    DEFF Research Database (Denmark)

    Lassen, L.H.; Jacobsen, V.B.; Haderslev, P.A.


    Calcitonin gene-related peptide (CGRP)-containing nerves are closely associated with cranial blood vessels. CGRP is the most potent vasodilator known in isolated cerebral blood vessels. CGRP can induce migraine attacks, and two selective CGRP receptor antagonists are effective in the treatment...... g/min) or placebo for 20 min was studied in 12 patients with migraine without aura outside attacks. Xenon-133 inhalation SPECT-determined regional cerebral blood flow (rCBF) and transcranial Doppler (TCD)-determined blood velocity (V-mean) in the middle cerebral artery (MCA), as well as the heart...

  1. Estimation of blood flow rates in large microvascular networks. (United States)

    Fry, Brendan C; Lee, Jack; Smith, Nicolas P; Secomb, Timothy W


    Recent methods for imaging microvascular structures provide geometrical data on networks containing thousands of segments. Prediction of functional properties, such as solute transport, requires information on blood flow rates also, but experimental measurement of many individual flows is difficult. Here, a method is presented for estimating flow rates in a microvascular network based on incomplete information on the flows in the boundary segments that feed and drain the network. With incomplete boundary data, the equations governing blood flow form an underdetermined linear system. An algorithm was developed that uses independent information about the distribution of wall shear stresses and pressures in microvessels to resolve this indeterminacy, by minimizing the deviation of pressures and wall shear stresses from target values. The algorithm was tested using previously obtained experimental flow data from four microvascular networks in the rat mesentery. With two or three prescribed boundary conditions, predicted flows showed relatively small errors in most segments and fewer than 10% incorrect flow directions on average. The proposed method can be used to estimate flow rates in microvascular networks, based on incomplete boundary data, and provides a basis for deducing functional properties of microvessel networks. © 2012 John Wiley & Sons Ltd.

  2. Intraoperative multi-exposure speckle imaging of cerebral blood flow. (United States)

    Richards, Lisa M; Kazmi, Sm Shams; Olin, Katherine E; Waldron, James S; Fox, Douglas J; Dunn, Andrew K


    Multiple studies have demonstrated that laser speckle contrast imaging (LSCI) has high potential to be a valuable cerebral blood flow monitoring technique during neurosurgery. However, the quantitative accuracy and sensitivity of LSCI is limited, and highly dependent on the exposure time. An extension to LSCI called multi-exposure speckle imaging (MESI) overcomes these limitations, and was evaluated intraoperatively in patients undergoing brain tumor resection. This clinical study ( n = 8) recorded multiple exposure times from the same cortical tissue area spanning 0.5-20 ms, and evaluated images individually as single-exposure LSCI and jointly using the MESI model. This study demonstrated that the MESI estimates provided the broadest flow sensitivity for sampling the flow magnitude in the human brain, closely followed by the shorter exposure times. Conservation of flow analysis on vascular bifurcations was used to validate physiological accuracy, with highly conserved flow estimates (goodness-of-fit with proper image calibration and acquisition, and was used to monitor blood flow changes after tissue cautery. Results from this study demonstrate that intraoperative MESI can be performed with high quantitative accuracy and sensitivity for cerebral blood flow monitoring.

  3. A dynamic model of renal blood flow autoregulation

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H; Marsh, D J


    To test whether a mathematical model combining dynamic models of the tubuloglomerular feedback (TGF) mechanism and the myogenic mechanism was sufficient to explain dynamic autoregulation of renal blood flow, we compared model simulations with experimental data. To assess the dynamic characteristics...... of renal autoregulation, a broad band perturbation of the arterial pressure was employed in both the simulations and the experiments. Renal blood flow and tubular pressure were used as response variables in the comparison. To better approximate the situation in vivo where a large number of individual...... data, which shows a unimodal curve for the admittance phase. The ability of the model to reproduce the experimental data supports the hypothesis that dynamic autoregulation of renal blood flow is due to the combined action of TGF and the myogenic response....

  4. Mediators of increased blood flow in porcine skin

    Directory of Open Access Journals (Sweden)

    H. D. Moore


    Full Text Available Nicotinates and benzalkonium chloride (B.Cl cause inflammatory changes in human skin, thought to be dependent upon prostaglandin formation. This study has examined the effects of hexyl-nicotinate (HN and B.Cl on blood flow in porcine skin. The role of prostaglandins and interleukin (IL-1 in the blood flow response has been investigated. Blood flow was increased by both HN and B.Cl, the response to B.Cl being more protracted. Cyclooxygenase inhibitor pretreatment reduced these responses. IL-1-like biological activity was identified in normal porcine epidermis and the amounts recovered from inflamed skin were similar. Thus prostaglandin formation in HN or B.Cl-induced inflammation, if IL-1 dependent, is not associated with the loss of significant amounts of the cytokine from the epidermis.

  5. Reduced blood flow to contracting skeletal muscle in ageing humans

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin; Hellsten, Ylva


    consequences of ageing and physical inactivity can be challenging; yet, observations from cross-sectional and longitudinal studies on the effects of physical activity have provided some insight. Physical activity has the potential to offset the age-related decline in blood flow to contracting skeletal muscle...... the O2 demand of the active skeletal muscle of aged individuals during conditions where systemic blood flow is not limited by cardiac output seems to a large extent to be related to the level of physical activity. This article is protected by copyright. All rights reserved.......The ability to sustain a given absolute submaximal workload declines with advancing age likely due to a lower level of blood flow and O2 delivery to the exercising muscles. Given that physical inactivity mimics many of the physiological changes associated with ageing, separating the physiological...

  6. Increased hepatic blood flow during enteral immune-enhancing diet gavage requires intact enterohepatic bile cycling. (United States)

    Nagengast, Andrea K; Hurt, Ryan T; Downard, Cynthia D; Smith, Jason W; Garrison, R Neal; Matheson, Paul J


    Total hepatic blood flow (HBF) via the hepatic artery and portal vein is highly dependent on gastrointestinal perfusion. During postprandial hyperemia, intestinal blood flow depends on nutrient composition, gastrointestinal location, and time. Immune-enhancing diets (IEDs) containing n-3 polyunsaturated fatty acids (PUFAs) selectively augment blood flow in the ileum at 60-120 min via a bile-dependent mechanism. My colleagues and I hypothesized that liver blood flow would be similarly affected by IEDs containing n-3 PUFAs. Mean arterial blood pressure, heart rate, and effective HBF (galactose clearance) were measured in anesthetized male Sprague-Dawley rats after gastric gavage of either a control diet (CD, Boost, Novartis) or an IED (Impact, Nestle Nutrition), with or without bile-duct ligation (BDL), and with or without supplemental bile (bovine, dried, unfractionated). Significance was assessed by 2-way ANOVA for repeated measures with the Tukey-Kramer honestly significant difference test. Compared with baseline levels, a CD increased HBF (peak at 40 min , *P < 0.05) whereas an IED increased HBF in two distinct peaks at 40 min (*P < 0.05) and 120 min (*P < 0.05), but BDL prevented both the early (CD and IED, †P < 0.05) and late peaks (IED, †P < 0.05). Bile supplementation in the CD + BDL or IED + BDL groups restored neither the CD peak nor the early or late IED peaks. HBF during absorptive intestinal hyperemia is modulated by a mechanism that requires an intact enterohepatic circulation. The early peaks at 40 min (CD or IED) were prevented by BDL, even though fat absorption in the proximal gut occurs by bile-independent direct absorption. Bile supplementation with the diet (CD + BDL or IED + BDL) was insufficient to restore HBF hyperemia, which implies that a relationship exists between intestinal and hepatic blood flow that is not solely dependent on bile-mediated intestinal fat absorption and bile recirculation. Copyright © 2014 Elsevier Inc. All rights

  7. Quantification of regional blood flow to canine flexor tendons

    Energy Technology Data Exchange (ETDEWEB)

    Weidman, K.A.; Simonet, W.T.; Wood, M.B.; Cooney, W.P.; Ilstrup, D.M.


    Although the blood supply and the microcirculation of flexor tendons have been studied and defined extensively using qualitative methods, the quantitative assessment of blood flow has been lacking because of the limitations of the available experimental techniques. The authors studied the regional blood supply to the flexor tendons of dogs by the technique of radionuclide-labeled microspheres. Seven adult mongrel dogs were used. Microsphere injection and tissue-counting techniques previously used for other tissues were applied. Samples of proximal, isthmus, and distal portions of the profundus and superficialis flexor tendons were harvested from each digital unit of available limbs from each dog. Mean (+/- SE) flows (ml/100 g dry tissue/min) were proximal profundus 1.78 +/- 0.60 and superficialis 7.10 +/- 1.50. The differences were significant. The study suggests that regional variation in blood flow to canine digital flexor tendons exists, so that a single value for blood flow to these tendons is not relevant. Furthermore, the study supports the concept of dual (vascular and synovial) nutrition to the digital flexor tendons in dogs. These observations may have implications regarding tendon repair techniques.

  8. Quantification of regional blood flow to canine flexor tendons. (United States)

    Weidman, K A; Simonet, W T; Wood, M B; Cooney, W P; Ilstrup, D M


    Although the blood supply and the microcirculation of flexor tendons have been studied and defined extensively using qualitative methods, the quantitative assessment of blood flow has been lacking because of the limitations of the available experimental techniques. We studied the regional blood supply to the flexor tendons of dogs by the technique of radionuclide-labeled microspheres. Seven adult mongrel dogs were used. Microsphere injection and tissue-counting techniques previously used for other tissues were applied. Samples of proximal, isthmus, and distal portions of the profundus and superficialis flexor tendons were harvested from each digital unit of available limbs from each dog. Mean (+/- SE) flows (ml/100 g dry tissue/min) were proximal profundus 1.78 +/- 0.60 and superficialis 7.10 +/- 1.50. The differences were significant (p less than 0.01). The study suggests that regional variation in blood flow to canine digital flexor tendons exists, so that a single value for blood flow to these tendons is not relevant. Furthermore, the study supports the concept of dual (vascular and synovial) nutrition to the digital flexor tendons in dogs. These observations may have implications regarding tendon repair techniques.

  9. Blood flow and microdialysis in the human femoral head

    DEFF Research Database (Denmark)

    Bøgehøj, Morten; Emmeluth, Claus; Overgaard, Søren


    ischemia and measure changes in blood flow. MATERIAL AND METHODS: In 9 patients undergoing total hip arthroplasty for primary osteoarthrosis, two MD catheters were inserted into the femoral head through two drill holes after the blood flow had been visualized by LD. Then primary samples were collected...... with the femoral head in situ; thereafter, the head was removed and samples were collected over the following 4 hours ex vivo. The variables obtained by MD were concentrations of glucose, lactate, pyruvate, and glycerol in extracellular fluid. RESULTS: The results showed development of ischemia...

  10. Endoscopic retrograde cholangiopancreatography causes reduced myocardial blood flow

    DEFF Research Database (Denmark)

    Christensen, M; Hendel, H W; Rasmussen, V


    BACKGROUND AND STUDY AIMS: Previous studies have shown that up to 50% of healthy patients may develop ST-segment changes during upper gastrointestinal endoscopy. The aim of the study was to evaluate myocardial blood flow in patients during endoscopic retrograde cholangiopancreatography (ERCP...... with either of the two methods, while two patients developed signs of ischemia during ERCP with both the Holter tape recording and on myocardial scintigraphy (P = 0.02). CONCLUSIONS: Patients undergoing ERCP may develop true myocardial ischemia with reduced myocardial blood flow. Although this is a small...

  11. 1-D blood flow modelling in a running human body. (United States)

    Szabó, Viktor; Halász, Gábor


    In this paper an attempt was made to simulate blood flow in a mobile human arterial network, specifically, in a running human subject. In order to simulate the effect of motion, a previously published immobile 1-D model was modified by including an inertial force term into the momentum equation. To calculate inertial force, gait analysis was performed at different levels of speed. Our results show that motion has a significant effect on the amplitudes of the blood pressure and flow rate but the average values are not effected significantly.

  12. Nocturnal foot blood flow in patients with arterial insufficiency

    DEFF Research Database (Denmark)

    Jelnes, Rolf; Tønnesen, K H


    Twenty-four hour continuous recording of xenon (133Xe) wash-out from the forefoot was performed on patients with normal circulations (n = 10) and on patients with different degrees of arterial insufficiency (n = 36). During day hours the calculated subcutaneous blood flow in the forefoot...... was on average the same in patients with normal circulations and in patients with different degrees of arterial insufficiency (mean: 2.0 +/- 0.8 ml min-1 100 g-1). During sleep the blood flow nearly doubled in patients with normal circulations; no systematic change was seen in patients with intermittent...

  13. Disparity in regional cerebral blood flow during electrically induced seizure

    DEFF Research Database (Denmark)

    Sestoft, D; Meden, P; Hemmingsen, R


    This is a presentation of 2 cases in which the intraictal regional cerebral blood flow distribution was measured with the 99mTc-HMPAO single photon emission computerized tomography technique during an electrically induced seizure. Although the seizure was verified as generalized on electroencepha......This is a presentation of 2 cases in which the intraictal regional cerebral blood flow distribution was measured with the 99mTc-HMPAO single photon emission computerized tomography technique during an electrically induced seizure. Although the seizure was verified as generalized...

  14. The effect of hyperosmotic solutions on the hepatic blood flow

    DEFF Research Database (Denmark)

    Winkler, K; Henriksen, Jens Henrik; Tygstrup, N


    infusions of hyperosmotic galactose (50%, 84-100 ml) and mannitol (25%, 100 ml), with physiological saline (100 ml) as control. Portal blood flow increased to a peak value of (39% [P = 0.06] galactose and 37%, [P = 0.06], mannitol) soon after stop of the hyperosmotic infusion. For galactose the change ended...... somewhat earlier than for mannitol. Saline induced a minor increase (15%). Similarly, increments of, on average, 144% of the hepatic blood flow rate was seen in six patients with cirrhosis, following infusion of hyperosmotic galactose, the increase being more pronounced than in the pigs. The causes...

  15. The role of macronutrients in gastrointestinal blood flow. (United States)

    de Aguilar-Nascimento, José Eduardo


    The presence of luminal nutrients after a meal increases gastrointestinal blood flow in a phenomenon called postprandial hyperemia. In many conditions related to splanchnic hypoperfusion, enteral nutrition may play a role in counterbalancing the installed splanchnic low-flow state by producing intestinal hyperemia. However, when the gut is hypoperfused there is a chance of enteral nutrition producing a mismatch of the oxygen demand: supply ratio with subsequence gut ischemia. This article aims to review the effects of macronutrients on gastrointestinal blood flow in both health and critical conditions, especially those related to hepatosplanchnic hypoperfusion. Splanchnic blood flow is related not only to the route (intravenous or enteral) and timing of nutritional support (during the course of the insult) but also to the composition of the formula. Critically ill patients with gut hypoperfusion may tolerate enteral nutrition, but this effect may be restricted to the early post-injury phase. During ischaemia reperfusion injury, immune nutrients may promote different outcomes: glutamine may protect whereas arginine may deteriorate the mucosal barrier and enhance permeability. Understanding the relationship between macronutrients and gastrointestinal blood flow is a major challenge. Ongoing research in nutritional support in hypoperfused, catecholamine-dependent patients will open the door to optimize the recovery of patients in critical care.

  16. [Endovascular treatment of persistent dysuria and chronic pelvic pain in women with pelvic varicose veins]. (United States)

    Neĭmark, A I; Shelkovnikova, N V


    The results of the examination and treatment of 16 patients aged from 26 to 46 years with persistent urinary disorders and chronic pelvic pain due to severe pelvic varicose veins are presented. Using ultrasound with color Doppler mapping and venography of renal and ovarian vein for evaluation of condition of the venous system of the pelvis, the significant dilation of the internal iliac, ovarian and uterine veins with a pronounced decrease in blood flow in veins up to the stasis of blood, accompanied by flow turbulence and powerful backflow of renal blood through ovarian veins were found in all patients. According to uroflowmetry, there was a decrease in detrusor tone and a violation of evacuation capacity of the bladder. Evaluation of microcirculation using LDF allowed to diagnose congestive hemodynamic type of microcirculation. Scleroembolization for varicose ovarian vein with Gianturco coil and ethoxysclerol was performed in all patients. Positive therapeutic effect in the form of eliminating varicose pelvic veins, pain relieve, disappearance of persistent dysuria, and the remission of chronic cystitis was achieved in 86% of women. This intervention provided the normal outflow of blood from the pelvic veins, contributed to the normalization of uroflowmetry data and restoration of normal microcirculation in the urinary bladder.

  17. Implementing a routine flow cytometry assay for nucleated red blood cell counts in cord blood units. (United States)

    Simard, C; Cloutier, M; Jobin, C; Dion, J; Fournier, D; Néron, S


    As required by standards organizations, Héma-Québec Cord Blood Bank performs enumeration of nucleated red blood cells (NRBCs) in cord blood units (CBUs). This study presents the validation and implementation approaches developed to transfer the routine NRBC enumeration from the manual blood film method to a flow cytometric assay. The flow cytometry method was adapted from Tsuji (Cytometry, 37, 1999, 291). This assay was validated to assess the specificity, detection limit, repeatability, and reproducibility of the method, including interoperator and interlaboratory testing. Finally, postimplementation follow-up and adjustments were performed for CBU over a 7-month period. Blood film and flow cytometry NRBC enumerations showed a strong correlation (n = 40; Pearson's r correlation = 0.90). Validation was successful as exemplified by the correlation in interlaboratory testing (n = 30; r = 0.98). During implementation, our routine laboratory analyses revealed that CBU with low NRBC content (≤2%), representing 26% of all CBU tested, resulted in 15% of repeated reading and/or staining and was the principal source of nonconformity. Small adjustments in the standard operating procedures (SOPs), including a fixed 200-event setting in the NRBC gate for the second reading of the replicates, have completely solved this issue. Flow cytometric NRBC enumerations, now implemented in Héma-Québec Public Cord Blood Bank, is an improvement in the efficiency of our operations by integrating the count for NRBC into our flow cytometry platform. © 2016 John Wiley & Sons Ltd.

  18. Blood Pump Development Using Rocket Engine Flow Simulation Technology (United States)

    Kiris, Cetin C.; Kwak, Dochan


    This viewgraph presentation provides information on the transfer of rocket engine flow simulation technology to work involving the development of blood pumps. Details are offered regarding the design and requirements of mechanical heart assist devices, or VADs (ventricular assist device). There are various computational fluid dynamics issues involved in the visualization of flow in such devices, and these are highlighted and compared to those of rocket turbopumps.

  19. The influence of steroids on vascular tension of isolated superficial veins of the nose and face during the estrous cycle of gilts. (United States)

    Grzegorzewski, W J; Chłopek, J; Tabecka-Łonczyńska, A; Stefańczyk-Krzymowska, S


    The arrangement of the superficial facial veins enables blood flow from the nasal cavity into the peripheral circulation by two pathways: through the frontal vein into the cavernous sinus and through the facial vein into the external jugular vein. The current study was designed to determine whether estradiol and progesterone affect the vascular tone of the superficial veins of the nose and face in cycling gilts (Sus scrofa f. domestica) and to analyze the immunolocalization of progesterone receptors and estradiol receptors in these veins. The influence of hormones on vascular tension differed depending on the type of vessel and the phase of the estrous cycle. Estradiol decreased vascular tension in the nasal vein during the follicular phase (Ptension in the frontal vein during the luteal phase (Ptension of the frontal vein (Ptension of the other veins (Psuperficial veins of the nose and face. In conclusion, the effect of ovarian steroid hormones on the vascular tension of the superficial veins of the nose and face in female pigs as well as the reactivity of these veins to steroid boar pheromones can affect the blood supply from the nasal cavity to the venous cavernous sinus. We propose that the ovarian steroid hormones that modulate the vascular tension of the nasal and facial veins may also influence the action of boar pheromones absorbed into the nasal mucosa in gilts and may reach the brain via local destination transfer.

  20. Nocturnal variations in peripheral blood flow, systemic blood pressure, and heart rate in humans

    DEFF Research Database (Denmark)

    Sindrup, J H; Kastrup, J; Christensen, H


    Subcutaneous adipose tissue blood flow rate, together with systemic arterial blood pressure and heart rate under ambulatory conditions, was measured in the lower legs of 15 normal human subjects for 12-20 h. The 133Xe-washout technique, portable CdTe(Cl) detectors, and a portable data storage uni.......0001). The synchronism of the nocturnal subcutaneous hyperemia and the decrease in systemic mean arterial blood pressure point to a common, possibly central nervous or humoral, eliciting mechanism.......Subcutaneous adipose tissue blood flow rate, together with systemic arterial blood pressure and heart rate under ambulatory conditions, was measured in the lower legs of 15 normal human subjects for 12-20 h. The 133Xe-washout technique, portable CdTe(Cl) detectors, and a portable data storage unit...

  1. [Ultrasound imaging of bridge vessel transplant used to reconstruct the tributary of middle hepatic vein in living donor liver transplantation]. (United States)

    Lu, Qiang; Luo, Yan; Yuan, Chao-xin; Yan, Lü-nan; Wu, Hong; Zhang, Zhong-wei


    To discuss the application of color Doppler ultrasound in the imaging of bridge vein transplant used to reconstruct the tributary of the middle hepatic vein in adult living donor liver transplantation (LDLT). From December 2005 to July 2006, 25 patients underwent the adult living donor liver transplantation with right lobe grafts without middle hepatic vein. Tributaries of middle hepatic vein larger than 5 mm were reconstructed with great saphenous vein. Types and numbers of reconstructed tributaries of middle hepatic vein were listed below: single V5 (n=8), double V5 (n=2), the V5 and V8 (n=9), V8 (n=6). The successive investigation of the vein grafts was performed by color Doppler ultrasound in the period of from postoperative 7 days to 8 months. All vein transplants were detected by color Doppler ultrasound. Among them, 34 vein transplants of 24 cases undergoing adult LDLT appeared patent, but one case was suspected to have reconstructed finally the bypass vessels for blood circle regardless of the grafted bridge vein probably occurring the thrombosis. Color Doppler ultrasound can precisely detect and appear the postoperative bridge vessel grafted, and also measure the blood flow velocity in grafted vein used to reconstruct the tributaries of the middle hepatic vein in LDLT.

  2. Blood flow analysis with considering nanofluid effects in vertical channel (United States)

    Noreen, S.; Rashidi, M. M.; Qasim, M.


    Manipulation of heat convection of copper particles in blood has been considered peristaltically. Two-phase flow model is used in a channel with insulating walls. Flow analysis has been approved by assuming small Reynold number and infinite length of wave. Coupled equations are solved. Numerical solution are computed for the pressure gradient, axial velocity function and temperature. Influence of attention-grabbing parameters on flow entities has been analyzed. This study can be considered as mathematical representation to the vibrance of physiological systems/tissues/organs provided with medicine.

  3. Chaotic Dynamics of Red Blood Cells in a Sinusoidal Flow (United States)

    Dupire, Jules; Abkarian, Manouk; Viallat, Annie


    We show that the motion of individual red blood cells in an oscillating moderate shear flow is described by a nonlinear system of three coupled oscillators. Our experiments reveal that the cell tank treads and tumbles either in a stable way with synchronized cell inclination, membrane rotation and hydrodynamic oscillations, or in an irregular way, very sensitively to initial conditions. By adapting our model described previously, we determine the theoretical diagram for the red cell motion in a sinusoidal flow close to physiological shear stresses and flow variation frequencies and reveal large domains of chaotic motions. Finally, fitting our observations allows a characterization of cell viscosity and membrane elasticity.

  4. The history of the microsphere method for measuring blood flows with special reference to myocardial blood flow: a personal memoir. (United States)

    Hoffman, Julien I E


    We use many types of equipment and technologies to make our measurements but give little thought to how they developed. Evolution was once described as a series of recoils from blind alleys, and this is exemplified by the gradual development of the microsphere method of measuring blood flows. The microsphere method is one of the most frequently used methods for measuring blood flow to organs and portions of organs. The method can measure myocardial blood flow with reasonable accuracy (within 10%) down to samples weighing >50 mg but probably will not do so for samples weighing 1-10 mg. Microspheres with diameters from 10 to 15 μm provide the best compromise between accurate flow measurement and retention in tissue. Radioactive labels have been almst entirely replaced by fluorescent labels, but colored microspheres and neutron-activated labels are also used.NEW & NOTEWORTHY The contributions of the various individuals who developed the microsphere method of measuring regional blood flows and how these advances took place are brought to light in this paper. Copyright © 2017 the American Physiological Society.

  5. Cerebral blood flow and intracranial pulsatility studied with MRI: measurement, physiological and pathophysiological aspects

    Energy Technology Data Exchange (ETDEWEB)

    Waahlin, Anders


    During each cardiac cycle pulsatile arterial blood inflates the vascular bed of the brain, forcing cerebrospinal fluid (CSF) and venous blood out of the cranium. Excessive arterial pulsatility may be part of a harmful mechanism causing cognitive decline among elderly. Additionally, restricted venous flow from the brain is suggested as the cause of multiple sclerosis. Addressing hypotheses derived from these observations requires accurate and reliable investigational methods. This work focused on assessing the pulsatile waveform of cerebral arterial, venous and CSF flows. The overall aim of this dissertation was to explore cerebral blood flow and intracranial pulsatility using MRI, with respect to measurement, physiological and pathophysiological aspects.Two-dimensional phase contrast magnetic resonance imaging (2D PCMRI) was used to assess the pulsatile waveforms of cerebral arterial, venous and CSF flow. The repeatability was assessed in healthy young subjects. The 2D PCMRI measurements of cerebral arterial, venous and CSF pulsatility were generally repeatable but the pulsatility decreased systematically during the investigation. A method combining 2D PCMRI measurements with invasive CSF infusion tests to determine the magnitude and distribution of compliance within the craniospinal system was developed and applied in a group of healthy elderly. The intracranial space contained approximately two thirds of the total craniospinal compliance. The magnitude of craniospinal compliance was less than suggested in previous studies. The vascular hypothesis for multiple sclerosis was tested. Venous drainage in the internal jugular veins was compared between healthy controls and multiple sclerosis patients using 2D PCMRI. For both groups, a great variability in the internal jugular flow was observed but no pattern specific to multiple sclerosis could be found. Relationships between regional brain volumes and potential biomarkers of intracranial cardiac-related pulsatile

  6. Oscillations and chaos in renal blood flow control

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H


    In normotensive, halothane-anesthetized rats, oscillations can be found both in the single-nephron blood flow and in the tubular pressure. Experimental data and computer simulations support the hypothesis that the oscillations are caused by the tubuloglomerular feedback (TGF) mechanism. Model...

  7. Disparity in regional cerebral blood flow during electrically induced seizure

    DEFF Research Database (Denmark)

    Sestoft, D; Meden, P; Hemmingsen, R


    This is a presentation of 2 cases in which the intraictal regional cerebral blood flow distribution was measured with the 99mTc-HMPAO single photon emission computerized tomography technique during an electrically induced seizure. Although the seizure was verified as generalized on electroencepha...

  8. Longitudinal Cerebral Blood Flow Changes during Speech in Hereditary Ataxia (United States)

    Sidtis, John J.; Strother, Stephen C.; Naoum, Ansam; Rottenberg, David A.; Gomez, Christopher


    The hereditary ataxias constitute a group of degenerative diseases that progress over years or decades. With principal pathology involving the cerebellum, dysarthria is an early feature of many of the ataxias. Positron emission tomography was used to study regional cerebral blood flow changes during speech production over a 21 month period in a…

  9. Abnormal blood flow in the sublingual microcirculation at high altitude

    NARCIS (Netherlands)

    Martin, Daniel S.; Ince, Can; Goedhart, Peter; Levett, Denny Z. H.; Grocott, Mike P. W.


    We report the first direct observations of deranged microcirculatory blood flow at high altitude, using sidestream dark-field imaging. Images of the sublingual microcirculation were obtained from a group of 12 volunteers during a climbing expedition to Cho Oyu (8,201 m) in the Himalayas.

  10. Whole-body vibration dosage alters leg blood flow

    NARCIS (Netherlands)

    Lythgo, Noel; Eser, Prisca; de Groot, Patricia; Galea, Mary

    The effect of whole-body vibration dosage on leg blood flow was investigated. Nine healthy young adult males completed a set of 14 random vibration and non-vibration exercise bouts whilst squatting on a Galileo 900 plate. Six vibration frequencies ranging from 5 to 30 Hz (5 Hz increments) were used

  11. [Assessing resveratrol effect on ocular blood flow in experiment]. (United States)

    Neroev, V V; Kiseleva, T N; Chudin, A V; Shchipanova, A I; Ramazanova, K A


    To study the effect of resveratrol on ocular blood flow in vivo in healthy rats and those that underwent retinal ischemia/reperfusion. The experimental study was performed on 40 Wistar rats (40 eyes). For ocular blood flow evaluation, color Doppler imaging (CDI), power Doppler (PD), and pulsed-wave spectral Doppler ultrasonography were performed using the Voluson E8 Expert ultrasonic diagnostic system (GE Healthcare). All rats were given resveratrol per os for 2 months of the study. Retinal ischemia/reperfusion injury was induced by a subconjunctival injection of endothelin-1. The control group included 10 intact animals. Signs of ischemic damage of the anterior and posterior eye segments were less pronounced in rats that were given resveratrol during both pre-ischemic (30 days) and post-ischemic (30 days) periods of follow-up. There was also a statistically significant increase in the peak systolic and end diastolic velocity of blood flow as well as a decrease in the resistive index of retrobulbar arteries in those rats that underwent ischemia/reperfusion as compared to the controls. Long-term resveratrol use (2 months) has proved effective in improving ocular blood flow in a rat model of retinal ischemia/reperfusion injury.

  12. Influence of blood flow on the coagulation cascade

    DEFF Research Database (Denmark)

    The influence of diffusion and convetive flows on the blood coagulation cascade is investigated for a controlled perfusion experiment. We present a cartoon model and reaction schemes for parts of the coagulation cascade with sunsequent set up of a mathematical model in two space dimensions plus one...

  13. Patterns of regional cerebral blood flow in acute stroke

    DEFF Research Database (Denmark)

    Olsen, T S; Skriver, E B


    In a consecutive group of 56 stroke patients the regional cerebral blood flow was measured within 84 hours after stroke. A 254 multidetector scintillation camera and the intracarotid Xenon-133 injection method was used to study rCBF. Typical rCBF-patterns are described and compared to the findings...

  14. Determinants of resting cerebral blood flow in sickle cell disease

    NARCIS (Netherlands)

    Bush, Adam M.; Borzage, Matthew T.; Choi, Soyoung; Václavů, Lena; Tamrazi, Benita; Nederveen, Aart J.; Coates, Thomas D.; Wood, John C.


    Stroke is common in children with sickle cell disease and results from an imbalance in oxygen supply and demand. Cerebral blood flow (CBF) is increased in patients with sickle cell disease to compensate for their anemia, but adequacy of their oxygen delivery has not been systematically demonstrated.

  15. Does isolated myocardial bridge really interfere with coronary blood flow?

    Directory of Open Access Journals (Sweden)

    Eid M. Daoud


    Conclusions: Myocardial bridging must be considered especially in patients at low risk for coronary atherosclerosis but with angina like chest pain or established myocardial ischemia. We suggest that coronary blood flow is decreased in the patients with MB compared with the patients having normal coronary.

  16. Neurophysiological Basis of Cerebral Blood Flow Control: An ...

    African Journals Online (AJOL)

    The book describes the current understanding of cerebral blood flow control. Subjects covered indude the autonomic nervous system, cellular neurophysiology and neurotransmitter systems. There is a good section on ionic channels and ionic pumps, as well as receptors and metaoolism of the central nervous system.

  17. Cerebral blood flow and oxidative metabolism during human endotoxemia

    DEFF Research Database (Denmark)

    Møller, Kirsten; Strauss, Gitte Irene; Qvist, Jesper


    and catecholamines was investigated in eight healthy young volunteers. Cerebral blood flow was measured by the Kety-Schmidt technique at baseline (during normocapnia and voluntary hyperventilation for calculation of subject-specific cerebrovascular CO reactivity), and 90 minutes after an intravenous bolus...

  18. Changes in Peak Expiratory Flow Rate, Blood Pressure and Pulse ...

    African Journals Online (AJOL)

    Changes in Peak Expiratory Flow Rate, Blood Pressure and Pulse Rate Following Ingestion of Increased Coffee Concentrations in Healthy Male Adults. ... It further indicates that, mild doses of coffee confer benefits on airflow in the lungs. While higher doses are also beneficial in improving airflow in the airway, such doses ...

  19. Changes in Peak Expiratory Flow Rate, Blood Pressure and Pulse ...

    African Journals Online (AJOL)

    We studied the effect of different concentrations of coffee on peak expiratory flow rate (PEFR), blood pressure and pulse rate in an attempt to determine some physiological effects of coffee intake. 18 apparently healthy adult males, age range 20 to 30 years, were recruited for the study over a three day period. Varying ...

  20. Increased cerebral blood flow in preeclampsia with magnetic resonance imaging

    NARCIS (Netherlands)

    Zeeman, Gerda G.; Hatab, MR; Twickler, DM


    Objective: The purpose of this study was to compare third trimester and nonpregnant cerebral blood flow of women with preeclampsia to normotensive control subjects with the use of magnetic resonance imaging techniques. Study design: Nine normotensive pregnant women and 12 untreated women with

  1. Velocity estimation using synthetic aperture imaging [blood flow

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Jensen, Jørgen Arendt


    Presented an approach for synthetic aperture blood flow ultrasound imaging. Estimates with a low bias and standard deviation can be obtained with as few as eight emissions. The performance of the new estimator is verified using both simulations and measurements. The results demonstrate that a ful...

  2. A New Technology for Detecting Cerebral Blood Flow

    DEFF Research Database (Denmark)

    Schytz, Henrik W; Guo, Song; Jensen, Lars T


    There is a need for real-time non-invasive, continuous monitoring of cerebral blood flow (CBF) during surgery, in intensive care units and clinical research. We investigated a new non-invasive hybrid technology employing ultrasound tagged near infrared spectroscopy (UT-NIRS) that may estimate...

  3. Modeling of internal carotid artery aneurysm and blood flow simulation. (United States)

    Xu, Bingqiang; Zhong, Hua; Duan, Shaoyin


    The rupture of aneurysm is quite common in the clinics, and is hazardous to patients. Its occurrence is considered to be related to the hemodynamic abnormalities. To construct the model of internal carotid artery aneurysm (ICA-A), and have a simulation of blood flow. Based on the CTA data from spiral CT scan, the ICA-A model was constructed, and the types of blood flow, wall shear stress (WSS), Von Mises stress (VMS) and pressure were simulated and calculated. ICA-A model has been built and shape is the same morphology as CT 3D-image. In the whole cardiac cycle, the blood flow of aneurysm body is swirl, its velocity is slower than that of aneurysm neck; the maximum deformation, wall shear stress, pressure and von mises stress of aneurysm wall is at the neck, the minimum is at the top. The highest value appeared at 0.52 s in the cardiac cycle of 0.74 s, the lowest is at 0.21 s. It is effective and practical to construct the model of ICA-A base on CTA data. Blood flow simulation of ICA-A will provide new basis for the study on the occurrence and development of aneurysm.

  4. Effect of labetalol on cerebral blood flow and middle cerebral arterial flow velocity in healthy volunteers

    DEFF Research Database (Denmark)

    Schroeder, T; Schierbeck, Jens; Howardy, P


    The effect of labetalol, a combined alpha- and beta-adrenoceptor antagonist, on the cerebral circulation was investigated in 7 normotensive subjects. Cerebral blood flow (CBF) was measured with the intravenous 133Xe method and mean flow velocity (Vmean) in the middle cerebral artery was determined...

  5. Cerebral blood flow links insulin resistance and baroreflex sensitivity.

    Directory of Open Access Journals (Sweden)

    John P Ryan

    Full Text Available Insulin resistance confers risk for diabetes mellitus and associates with a reduced capacity of the arterial baroreflex to regulate blood pressure. Importantly, several brain regions that comprise the central autonomic network, which controls the baroreflex, are also sensitive to the neuromodulatory effects of insulin. However, it is unknown whether peripheral insulin resistance relates to activity within central autonomic network regions, which may in turn relate to reduced baroreflex regulation. Accordingly, we tested whether resting cerebral blood flow within central autonomic regions statistically mediated the relationship between insulin resistance and an indirect indicator of baroreflex regulation; namely, baroreflex sensitivity. Subjects were 92 community-dwelling adults free of confounding medical illnesses (48 men, 30-50 years old who completed protocols to assess fasting insulin and glucose levels, resting baroreflex sensitivity, and resting cerebral blood flow. Baroreflex sensitivity was quantified by measuring the magnitude of spontaneous and sequential associations between beat-by-beat systolic blood pressure and heart rate changes. Individuals with greater insulin resistance, as measured by the homeostatic model assessment, exhibited reduced baroreflex sensitivity (b = -0.16, p < .05. Moreover, the relationship between insulin resistance and baroreflex sensitivity was statistically mediated by cerebral blood flow in central autonomic regions, including the insula and cingulate cortex (mediation coefficients < -0.06, p-values < .01. Activity within the central autonomic network may link insulin resistance to reduced baroreflex sensitivity. Our observations may help to characterize the neural pathways by which insulin resistance, and possibly diabetes mellitus, relates to adverse cardiovascular outcomes.

  6. Ultrasonic Doppler blood flow meter for extracorporeal circulation (United States)

    Dantas, Ricardo G.; Costa, Eduardo T.; Maia, Joaquim M.; Nantes Button, Vera L. d. S.


    In cardiac surgeries it is frequently necessary to carry out interventions in internal heart structures, and where the blood circulation and oxygenation are made by artificial ways, out of the patient's body, in a procedure known as extracorporeal circulation (EC). During this procedure, one of the most important parameters, and that demands constant monitoring, is the blood flow. In this work, an ultrasonic pulsed Doppler blood flowmeter, to be used in an extracorporeal circulation system, was developed. It was used a 2 MHz ultrasonic transducer, measuring flows from 0 to 5 liters/min, coupled externally to the EC arterial line destined to adults perfusion (diameter of 9.53 mm). The experimental results using the developed flowmeter indicated a maximum deviation of 3.5% of full scale, while the blood flow estimator based in the rotation speed of the peristaltic pump presented deviations greater than 20% of full scale. This ultrasonic flowmeter supplies the results in a continuous and trustworthy way, and it does not present the limitations found in those flowmeters based in other transduction methods. Moreover, due to the fact of not being in contact with the blood, it is not disposable and it does not need sterilization, reducing operational costs and facilitating its use.

  7. Coded ultrasound for blood flow estimation using subband processing

    DEFF Research Database (Denmark)

    Gran, Fredrik; Udesen, Jesper; Nielsen, Michael bachmann


    This paper further investigates the use of coded excitation for blood flow estimation in medical ultrasound. Traditional autocorrelation estimators use narrow-band excitation signals to provide sufficient signal-to-noise-ratio (SNR) and velocity estimation performance. In this paper, broadband...... the excitation signal is broadband and has good spatial resolution after pulse compression. Two different codin-schemes are used in this paper, Barker codes and Golay codes. The performance of the codes for velocity estimation is compared to a conventional approach transmitting a narrow-band pulse. The study...... was carried out using an experimental ultrasound scanner and a commercial linear array 7 MHz transducer. A circulating flow rig was scanned with a beam-to-flow angle of 60 degrees. The flow in the rig was laminar and had a parabolic flow-profile with a peak velocity of 0.09 m/s. The mean relative standard...

  8. Vasopressin-induced changes in splanchnic blood flow and hepatic and portal venous pressures in liver resection. (United States)

    Bown, L Sand; Ricksten, S-E; Houltz, E; Einarsson, H; Söndergaard, S; Rizell, M; Lundin, S


    To minimize blood loss during hepatic surgery, various methods are used to reduce pressure and flow within the hepato-splanchnic circulation. In this study, the effect of low- to moderate doses of vasopressin, a potent splanchnic vasoconstrictor, on changes in portal and hepatic venous pressures and splanchnic and hepato-splanchnic blood flows were assessed in elective liver resection surgery. Twelve patients were studied. Cardiac output (CO), stroke volume (SV), mean arterial (MAP), central venous (CVP), portal venous (PVP) and hepatic venous pressures (HVP) were measured, intraoperatively, at baseline and during vasopressin infusion at two infusion rates (2.4 and 4.8 U/h). From arterial and venous blood gases, the portal (splanchnic) and hepato-splanchnic blood flow changes were calculated, using Fick's equation. CO, SV, MAP and CVP increased slightly, but significantly, while systemic vascular resistance and heart rate remained unchanged at the highest infusion rate of vasopressin. PVP was not affected by vasopressin, while HVP increased slightly. Vasopressin infusion at 2.4 and 4.8 U/h reduced portal blood flow (-26% and -37%, respectively) and to a lesser extent hepato-splanchnic blood flow (-9% and -14%, respectively). The arterial-portal vein lactate gradient was not significantly affected by vasopressin. Postoperative serum creatinine was not affected by vasopressin. Short-term low to moderate infusion rates of vasopressin induced a splanchnic vasoconstriction without metabolic signs of splanchnic hypoperfusion or subsequent renal impairment. Vasopressin caused a centralization of blood volume and increased cardiac output. Vasopressin does not lower portal or hepatic venous pressures in this clinical setting. © 2016 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  9. Vector flow imaging techniques: An innovative ultrasonographic technique for the study of blood flow. (United States)

    Goddi, Alfredo; Fanizza, Marianna; Bortolotto, Chandra; Raciti, Maria Vittoria; Fiorina, Ilaria; He, Xujin; Du, Yigang; Calliada, Fabrizio


    Doppler ultrasonography is routinely used to identify abnormal blood flow. Nevertheless, conventional Doppler can be used to determine only the axial component of blood flow velocity and is angle dependent. A new method of multidimensional angle-independent estimation of flow velocity, called Vector Flow Imaging (VFI), has been proposed. It quantitatively evaluates the true velocity vector's amplitude and direction at any location into a vessel and displays a more intuitive depiction of the flow movements. High frame rate VFI, based on plane wave imaging, allows a detailed dynamic visualization of complex flow by showing even transient events, otherwise undetectable. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 45:582-588, 2017. © 2017 Wiley Periodicals, Inc.

  10. unilateral idiopathic dilated episcleral vein with secondary open ...

    African Journals Online (AJOL)


    TO Otulana, OO Onabolu, VO Fafiolu. 22 flourescien angiography to exclude lesions of the vortex veins are all useful investigations to determine the aetiology of dilated episcleral vessels. Orbital ocular Doppler imaging is important in imaging orbital and ocular blood flow, especially in cases of fistula and varix.3, 13, 15, 17.

  11. Uterine artery blood flow velocity waveforms during uterine contractions. (United States)

    Li, H; Gudmundsson, S; Olofsson, P


    No quantitative or qualitative Doppler velocimetry classification of vascular flow resistance covering all stages of forward and reversed flows exists. The objective of this study was to characterize uterine artery (UtA) flow velocity waveforms (FVWs) obtained during an oxytocin challenge test (OCT) and compare them to FVWs in spontaneous normal labor. Uterine artery Doppler velocimetry was performed during and between uterine contractions in 61 high-risk pregnancies subjected to an OCT and in 20 normal pregnancies undergoing spontaneous labor. FVWs were classified relative to the presence of forward/absent/reversed flow during systole and diastole, and the time-averaged flow velocity over the heart cycle. Eleven different FVW classes were identified. No relationship between FVWs recorded during uterine inertia and contractions was found (P >/= 0.2). In both groups, only forward FVWs were recorded between contractions, whereas during contractions flow reversal was more common in the OCT group (P uterine contractions were not predicted by flow patterns recorded during uterine inertia. Reversal of flow direction was more common during oxytocin-induced uterine contractions than during spontaneous contractions. In cases of predominantly reversed flow, domains of the uterus may be supplied by blood from the contralateral UtA. These observations give new insights into the circulatory dynamics of the uterus during labor, and also point to a possible vasoconstrictory effect in the UtAs of oxytocin at high concentrations. Copyright 2003 ISUOG. Published by John Wiley & Sons, Ltd.

  12. Blood flow in the cerebral venous system: modeling and simulation. (United States)

    Miraucourt, Olivia; Salmon, Stéphanie; Szopos, Marcela; Thiriet, Marc


    The development of a software platform incorporating all aspects, from medical imaging data, through three-dimensional reconstruction and suitable meshing, up to simulation of blood flow in patient-specific geometries, is a crucial challenge in biomedical engineering. In the present study, a fully three-dimensional blood flow simulation is carried out through a complete rigid macrovascular circuit, namely the intracranial venous network, instead of a reduced order simulation and partial vascular network. The biomechanical modeling step is carefully analyzed and leads to the description of the flow governed by the dimensionless Navier-Stokes equations for an incompressible viscous fluid. The equations are then numerically solved with a free finite element software using five meshes of a realistic geometry obtained from medical images to prove the feasibility of the pipeline. Some features of the intracranial venous circuit in the supine position such as asymmetric behavior in merging regions are discussed.

  13. Effects of midazolam on cerebral blood flow in human volunteers

    Energy Technology Data Exchange (ETDEWEB)

    Forster, A.; Juge, O.; Morel, D.


    The effects of intravenously administered midazolam on cerebral blood flow were evaluated in eight healthy volunteers using the /sup 133/Xe inhalation technique. Six minutes after an intravenous dose of 0.15 mg/kg midazolam, the cerebral blood flow decreased significantly (P less than 0.001) from a value of 40.6 +/- 3.3 to a value of 27.0 +/- 5.0 ml . 100 g-1 . min-1. Cerebrovascular resistance (CVR) increased from 2.8 +/- 0.2 to 3.9 to 0.6 mmHg/(ml . 100 g-1 . min-1)(P less than 0.001). Mean arterial blood pressure decreased significantly (P less than 0.05) from 117 +/- 8 to 109 +/- 9 mmHg and arterial carbon dioxide tension increased from 33.9 +/- 2.3 to 38.6 +/- 3.2 mmHg (P less than 0.05). Arterial oxygen tension remained stable throughout the study, 484 +/- 95 mmHg before the administration of midazolam and 453 +/- 76 mmHg after. All the subjects slept after the injection of the drug and had anterograde amnesia of 24.5 +/- 5 min. The decrease in mean arterial blood pressure was probably not important since it remained in the physiologic range for cerebral blood flow autoregulation. The increase in arterial carbon dioxide tension observed after the midazolam injection may have partially counteracted the effect of this new benzodiazepine on cerebral blood flow. Our data suggest that midazolam might be a safe agent to use for the induction of anethesia in neurosurgical patients with intracranial hypertension.

  14. MR assessment of absolute myocardial blood flow and vasodilator flow reserve in patients with hypertrophic cardiomyopathy

    Energy Technology Data Exchange (ETDEWEB)

    Kawada, Nanaka; Sakuma, Hajime; Takeda, Kan; Nakagawa, Tsuyoshi; Yamakado, Tetsu; Nakano, Takeshi [Mie Univ., Tsu (Japan). School of Medicine


    Absolute coronary blood flow per myocardial mass and coronary flow reserve for the entire left ventricle were evaluated in normals and in patients with hypertrophic cardiomyopathy (HCM) by using fast cine MR imaging and fast velocity encoded cine (VENC) MR imaging. Nine healthy volunteers and 8 patients with HCM were studied with a 1.5 T imager. Breath-hold cine MR images encompassing the whole left ventricle were acquired on short axis imaging planes in order to evaluate myocardial mass. A fast VENC MR images were obtained to measure blood flow volume in the coronary sinus before and after dipyridamole administration (TR/TE=15/5 ms, FOV=28 x 22 cm, slice thickness=5 mm). Coronary flow reserve was calculated as a ratio of hyperemic to baseline coronary flow volumes. In the baseline state, coronary blood flow per myocardial mass was significantly lower in patients with HCM than in normal myocardium (0.56{+-}0.23 vs. 0.78{+-}0.27 ml/min/g, p<0.05). After dipyridamole administration, coronary blood flow per myocardial mass in patients with HCM increased substantially less than that in healthy subjects (0.99{+-}0.38 vs. 2.22{+-}0.55 ml/min/g, p<0.01), resulting in the significantly decreased coronary flow reserve ratio in HCM in comparison with that in normal myocardium (1.86{+-}0.56 vs. 3.11{+-}1.37, p<0.05). In conclusion, breath-hold velocity encoded cine MR imaging is a noninvasive technique which can provide assessments of altered coronary blood flow volume per myocardial mass and vasodilator flow reserve in patients with HCM. (author)

  15. A Reconstruction Method of Blood Flow Velocity in Left Ventricle Using Color Flow Ultrasound

    Directory of Open Access Journals (Sweden)

    Jaeseong Jang


    Full Text Available Vortex flow imaging is a relatively new medical imaging method for the dynamic visualization of intracardiac blood flow, a potentially useful index of cardiac dysfunction. A reconstruction method is proposed here to quantify the distribution of blood flow velocity fields inside the left ventricle from color flow images compiled from ultrasound measurements. In this paper, a 2D incompressible Navier-Stokes equation with a mass source term is proposed to utilize the measurable color flow ultrasound data in a plane along with the moving boundary condition. The proposed model reflects out-of-plane blood flows on the imaging plane through the mass source term. The boundary conditions to solve the system of equations are derived from the dimensions of the ventricle extracted from 2D echocardiography data. The performance of the proposed method is evaluated numerically using synthetic flow data acquired from simulating left ventricle flows. The numerical simulations show the feasibility and potential usefulness of the proposed method of reconstructing the intracardiac flow fields. Of particular note is the finding that the mass source term in the proposed model improves the reconstruction performance.

  16. Phenotypic heterogeneity in the endothelium of the human vortex vein system. (United States)

    Yu, Paula K; Tan, Priscilla E Z; Cringle, Stephen J; McAllister, Ian L; Yu, Dao-Yi


    The vortex vein system is the drainage pathway for the choroidal circulation and serves an important function in the effective drainage of the exceptionally high blood flow from the choroidal circulation. As there are only 4-6 vortex veins, a large volume of blood must be drained from many choroidal veins into each individual vortex vein. The vortex vein system must also cope with passing through tissues of different rigidity and significant pressure gradient as it transverses from the intrao-cular to the extra-ocular compartments. However, little is known about how the vortex vein system works under such complex situations in both physiological and pathological condition. Endothelial cells play a vital role in other vascular systems, but they have not been studied in detail in the vortex vein system. The purpose of this study is to characterise the intracellular structures and morphology in both the intra-and extra-ocular regions of the human vortex vein system. We hypothesise the presence of endothelial phenotypic heterogeneity through the vortex vein system. The inferior temporal vortex vein system from human donor eyes were obtained and studied histologically using confocal microscopy. The f-actin cytoskeleton and nuclei were labelled using Alexa Fluor conjugated Phalloidin and YO-PRO-1. Eight regions of the vortex vein system were examined with the venous endothelium studied in detail with quantitative data obtained for endothelial cell and nuclei size and shape. Significant endothelial phenotypic heterogeneity was found throughout the vortex vein system with the most obvious differences observed between the ampulla and its downstream regions. Variation in the distribution pattern of smooth muscle cells, in particular the absence of smooth muscle cells around the ampulla, was noted. Our results suggest the presence of significantly different haemodynamic forces in different regions of the vortex vein system and indicate that the vortex vein system may play

  17. Influence of Gravity on Blood Volume and Flow Distribution (United States)

    Pendergast, D.; Olszowka, A.; Bednarczyk, E.; Shykoff, B.; Farhi, L.


    In our previous experiments during NASA Shuttle flights SLS 1 and 2 (9-15 days) and EUROMIR flights (30-90 days) we observed that pulmonary blood flow (cardiac output) was elevated initially, and surprisingly remained elevated for the duration of the flights. Stroke volume increased initially and then decreased, but was still above 1 Gz values. As venous return was constant, the changes in SV were secondary to modulation of heart rate. Mean blood pressure was at or slightly below 1 Gz levels in space, indicating a decrease in total peripheral resistance. It has been suggested that plasma volume is reduced in space, however cardiac output/venous return do not return to 1 Gz levels over the duration of flight. In spite of the increased cardiac output, central venous pressure was not elevated in space. These data suggest that there is a change in the basic relationship between cardiac output and central venous pressure, a persistent "hyperperfusion" and a re-distribution of blood flow and volume during space flight. Increased pulmonary blood flow has been reported to increase diffusing capacity in space, presumably due to the improved homogeneity of ventilation and perfusion. Other studies have suggested that ventilation may be independent of gravity, and perfusion may not be gravity- dependent. No data for the distribution of pulmonary blood volume were available for flight or simulated microgravity. Recent studies have suggested that the pulmonary vascular tree is influenced by sympathetic tone in a manner similar to that of the systemic system. This implies that the pulmonary circulation is dilated during microgravity and that the distribution of blood flow and volume may be influenced more by vascular control than by gravity. The cerebral circulation is influenced by sympathetic tone similarly to that of the systemic and pulmonary circulations; however its effects are modulated by cerebral autoregulation. Thus it is difficult to predict if cerebral perfusion is

  18. [Assessment of maternal cerebral blood flow in patients with preeclampsia]. (United States)

    Mandić, Vesna; Miković, Zeljko; Dukić, Milan; Vasiljević, Mladenko; Filimonović, Dejan; Bogavac, Mirjana


    Systemic vasoconstriction in preeclamptic patients increases vascular resistance, and is manifested by increased arterial blood flow velocity. The aim of the study is to evaluate if there is a change of Doppler indices in maternal medial cerbral artery (MCA) in severe preeclampsia due to: 1) severity of clinical symptoms, 2) the begining of eclamptic attack and 3) the application of anticonvulsive therapy. A prospective clinical study included 92 pregnant women, gestational age 28-36 weeks. They were divided into three groups: normotensive (n=30), mild preeclampsia (n=33), and severe preeclampsia (n=29). We investigated maternal cerebral circulation by assessing the MCA. We registrated: pulsatility index (Pi), resistance index (Ri), systolic/diastolic ratio (S/D), and the maximum systolic, end diastolic and medium velocity. Patients with severe preeclampsia were divided into two subgroups. subgroup 1 included patients without symptoms of threatening eclampsia (n=18; 62.06%); while subgroup 2 included those with symptoms of preeclampsia (n=11; 37.94%). All patients with severe preeclampsia were treated with magnesium sulfate (MgSO4), and cerebral blood flow was measured before and after the treatment. Statistical analysis was done by oneway ANOVA, Student t-test and t-paired sample test. The difference was considered to be significant if ppreeclamsia we registrated significantly increased values of all velocities (patients with signs of threatening eclampsia). After MgSO4 treatment in patients with severe preeclampsia significantly decreased values of Pi, Ri, S/D ratio and all velocities were registered. In the studied group of patients with severe preclampsia we found increased velocity values, Pi and Ri, especially in patients with signs of threatened eclampsia, suggesting that blood vessels changes are most prominent in severe preeclampsia. Cerebral blood flow meassurements can be used as a clinical test for the prediction of eclampsia. Magnesium-sulfate (MgSO4

  19. Volumetric lattice Boltzmann simulation for blood flow in aorta arteries (United States)

    Deep, Debanjan; Yu, Huidan (Whitney); Teague, Shawn


    Complicated moving boundaries pose a major challenge in computational fluid dynamics for complex flows, especially in the biomechanics of both blood flow in the cardiovascular system and air flow in the respiratory system where the compliant nature of the vessels can have significant effects on the flow rate and wall shear stress. We develop a computation approach to treat arbitrarily moving boundaries using a volumetric representation of lattice Boltzmann method, which distributes fluid particles inside lattice cells. A volumetric bounce-back procedure is applied in the streaming step while momentum exchange between the fluid and moving solid boundary are accounted for in the collision sub-step. Additional boundary-induced migration is introduced to conserve fluid mass as the boundary moves across fluid cells. The volumetric LBM (VLBM) is used to simulate blood flow in both normal and dilated aorta arteries. We first compare flow structure and pressure distribution in steady state with results from Navier-Stokes based solver and good agreements are achieved. Then we focus on wall stress within the aorta for different heart pumping condition and present quantitative measurement of wall shear and normal stress.

  20. The influence of steroids on the vascular tension of isolated superficial nasal and facial veins in gilts during sexual maturation. (United States)

    Grzegorzewski, W J; Muszak, J; Tabecka-Łonczyńska, A; Stefańczyk-Krzymowska, S


    The arrangement of the superficial facial veins enables blood flow from the nasal cavity into the peripheral circulation by two pathways: through the facial vein into the external jugular vein and through the frontal vein into the cavernous sinus. The venous cavernous sinus is the site where hormones and pheromones permeate from venous blood into the arterial blood supplying the brain and hypophysis. The present study was designed to: (1) determine whether estradiol (E2) and progesterone (P4) affect the vascular tone of the superficial veins of the nose and face in maturating prepubertal gilts (PP) and in prepubertal gilts deprived of ovarian hormones (PPov), and (2) to analyze the immunolocalization of progesterone receptors (PR), and estradiol receptors alpha (ER alpha) and beta (ER beta) in these veins. The influence of hormones on the vascular tension differed depending on the type of vessel, the hormonal status and dose of hormone used. Estradiol decreased the vascular tension in the nasal and facial veins of PP gilts (P tension in the proximal and distal parts of the facial vein (P tension in the proximal segment of the nasal vein and in the distal segment of the frontal and facial veins, and decreased the tension in the distal segment of the nasal and facial veins (P tension of distal and proximal segments of the nasal vein (P tension of the distal part of the nasal vein (P superficial nasal and facial veins. In conclusion, the ovarian steroid hormones that modulate the vascular tension of the nasal and facial veins in prepubertal gilts may influence the transfer of boar pheromones from the nasal mucosa to the brain via local humoral pathway during sexual maturation.

  1. Rheology dynamics of the blood and plasma of rats after transdermal laser irradiation of the tail vein in the infrared range (United States)

    Yamaikina, I. V.; Mansurov, V. A.; Gorbunova, N. B.; Batai, L. E.; Ulashchik, V. S.; Orlovich, V. A.


    Single transdermal laser irradiation of the tail vein of males of white mongrel rats with an average mass of 350-400 g in three different regimes has been carried out. The irradiation doses were chosen to be intermediate between therapeutic and surgical ones, and the radiation wavelengths were 806 nm and 2 μm. The dynamics of the packed cell volume, deformability and cytometric indices of erythrocytes, and of the plasma and blood viscosity have been investigated. The rheological and cytometric changes in the blood caused by the irradiation stayed for several days. The observed rheologial changes are due to the removal of irradiation-damaged erythrocytes and the arrival in the blood channel of young and highly deformable red cells.

  2. Ozone Therapy on Cerebral Blood Flow: A Preliminary Report

    Directory of Open Access Journals (Sweden)

    Bernardino Clavo


    Full Text Available Ozone therapy is currently being used in the treatment of ischemic disorders, but the underlying mechanisms that result in successful treatment are not well known. This study assesses the effect of ozone therapy on the blood flow in the middle cerebral and common carotid arteries. Seven subjects were recruited for the therapy that was performed by transfusing ozone-enriched autologous blood on 3 alternate days over 1 week. Blood flow quantification in the common carotid artery (n = 14 was performed using color Doppler. Systolic and diastolic velocities in the middle cerebral artery (n = 14 were estimated using transcranial Doppler. Ultrasound assessments were conducted at the following three time points: 1 basal (before ozone therapy, 2 after session #3 and 3 1 week after session #3. The common carotid blood flow had increased by 75% in relation to the baseline after session #3 (P < 0.001 and by 29% 1 week later (P = 0.039. In the middle cerebral artery, the systolic velocity had increased by 22% after session #3 (P = 0.001 and by 15% 1 week later (P = 0.035, whereas the diastolic velocity had increased by 33% after session #3 (P < 0.001 and by 18% 1 week later (P = 0.023. This preliminary Doppler study supports the clinical experience of achieving improvement by using ozone therapy in peripheral ischemic syndromes. Its potential use as a complementary treatment in cerebral low perfusion syndromes merits further clinical evaluation.

  3. Modulation of radial blood flow during Braille character discrimination task. (United States)

    Murata, Jun; Matsukawa, K; Komine, H; Tsuchimochi, H


    Human hands are excellent in performing sensory and motor function. We have hypothesized that blood flow of the hand is dynamically regulated by sympathetic outflow during concentrated finger perception. To identify this hypothesis, we measured radial blood flow (RBF), radial vascular conductance (RVC), heart rate (HR), and arterial blood pressure (AP) during Braille reading performed under the blind condition in nine healthy subjects. The subjects were instructed to read a flat plate with raised letters (Braille reading) for 30 s by the forefinger, and to touch a blank plate as control for the Braille discrimination procedure. HR and AP slightly increased during Braille reading but remained unchanged during the touching of the blank plate. RBF and RVC were reduced during the Braille character discrimination task (decreased by -46% and -49%, respectively). Furthermore, the changes in RBF and RVC were much greater during the Braille character discrimination task than during the touching of the blank plate (decreased by -20% and -20%, respectively). These results have suggested that the distribution of blood flow to the hand is modulated via sympathetic nerve activity during concentrated finger perception.

  4. Ozone Therapy on Cerebral Blood Flow: A Preliminary Report (United States)


    Ozone therapy is currently being used in the treatment of ischemic disorders, but the underlying mechanisms that result in successful treatment are not well known. This study assesses the effect of ozone therapy on the blood flow in the middle cerebral and common carotid arteries. Seven subjects were recruited for the therapy that was performed by transfusing ozone-enriched autologous blood on 3 alternate days over 1 week. Blood flow quantification in the common carotid artery (n = 14) was performed using color Doppler. Systolic and diastolic velocities in the middle cerebral artery (n = 14) were estimated using transcranial Doppler. Ultrasound assessments were conducted at the following three time points: 1) basal (before ozone therapy), 2) after session #3 and 3) 1 week after session #3. The common carotid blood flow had increased by 75% in relation to the baseline after session #3 (P ozone therapy in peripheral ischemic syndromes. Its potential use as a complementary treatment in cerebral low perfusion syndromes merits further clinical evaluation. PMID:15841265

  5. Blood flow and oxygenation in peritendinous tissue and calf muscle during dynamic exercise in humans

    DEFF Research Database (Denmark)

    Boushel, Robert Christopher; Langberg, H; Green, Sara Marie Ehrenreich


    , and (2) whether blood flow is coupled to oxidative metabolism. 2. Seven individuals performed dynamic plantar flexion from 1 to 9 W. Radial artery and popliteal venous blood were sampled for O2, peritendinous blood flow was determined by 133Xe-washout, calf blood flow by plethysmography, cardiac output...

  6. Retrobulbar ocular blood flow changes after phacoemulsification in patients

    Directory of Open Access Journals (Sweden)

    Yin-Ying Zhao


    Full Text Available AIM:To evaluate retrobulbar ocular blood flow changes after phacoemulsification.METHODS:Prospective consecutive study. Forty-six eyes from 46 cataract patients scheduled for phacoemulsification surgery at Affiliated Eye Hospital, Wenzhou Medical College were recruited, of which 22 patients with normal blood pressure and 24 patients with hypertension. All eyes were examined by a color Doppler imaging at before, 4h, 1d after surgery. Resistance indexes(RIs, peak systolic flow velocity(PSV, end-diastolic flow velocity(EDVwere assessed in the ophthalmic artery(OA, central retinal artery(CRA, and short posterior ciliary arteries(PCA.RESULTS:RIs of a retrobulbar ocular vessels are stable at 4h and 1d in both group postoperatively. A slight decrease in PSV of PCA in hypertension patients, while a slightly increase in normal patients at 4h postoperatively was observed(10.22±4.39 vs 11.73±4.69. There were no significant difference between them(P=0.089. PSV and EDV in CRA are lower in hypertension patients but without statistical significance compared with normal patients. There was a statistically significant decrease in EDV of the PCA in hypertension patients at 4h postoperatively compared with preoperatively(3.23±1.10 vs 3.63±1.15,P=0.036. CONCLUSION:Retinal blood flow was disturbed at super-early after phacoemulsification. Age and hypertension are important risk factors to phacoemusification.

  7. Narcolepsy: regional cerebral blood flow during sleep and wakefulness

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, F.; Meyer, J.S.; Karacan, I.; Yamaguchi, F.; Yamamoto, M.


    Serial measurements of regional cerebral blood flow were made by the 135Xe inhalation method during the early stages of sleep and wakefulness in eight normal volunteers and 12 patients with narcolepsy. Electroencephalogram, electro-oculogram, and submental electromyogram were recorded simultaneously. In normals, mean hemispheric gray matter blood flow (Fg) during stages I and II sleep was significantly less than waking values. Maximum regional blood flow decreases during sleep occurred in the brainstem-cerebellar, right inferior temporal, and bilateral frontal regions. In patients with narcolepsy, mean hemispheric Fg while awake was 80.5 +- 13 ml per 100 gm brain per minute. During REM sleep, mean hemispheric Fg increased concurrently with large increases in brainstem-cerebellar region flow. During stages I and II sleep without REM, there were significant increases in mean hemispheric Fg and brainstem-cerebellar Fg, just the opposite of changes in normals. In narcolepsy, there appears to be a reversal of normal cerebral deactivation patterns, particularly involving the brainstem, during stages I and II sleep.

  8. Cerebral blood flow in patients with dementia of Alzheimer's type

    DEFF Research Database (Denmark)

    Postiglione, A; Lassen, N A; Holman, B L


    of the disease. Lateral CBF asymmetry is also very frequent; speech disorders are highly characteristic of left-sided flow reduction, while visuospatial apraxia is dominating in the right-sided cases. In advanced and severe cases of AD, CBF and metabolism tend to be more uniformly reduced throughout the cortex......In the normal brain as well as in Alzheimer's disease (AD), regional cerebral blood flow (CBF) is coupled to metabolic demand and, therefore, changes in CBF reflect variations in neuronal metabolism. The use of radionuclide techniques, such as positron emission tomography (PET) and single photon......-parieto-temporal CBF reduction is highly diagnostic for AD, despite the fact that a similar CBF pattern could also be observed in other types of dementia. Many AD patients with parieto-temporal flow reduction also have a diffuse flow reduction in the frontal cortical areas, particularly in advanced stages...

  9. Endothelial-dependent vasodilators preferentially increase subendocardial blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Pelc, L.R.; Gross, G.J.; Warltier, D.C.


    Interference with arachidonic acid metabolism on the effect of acetylcholine (Ach) or arachidonic acid (AA) to preferentially increase subendocardial perfusion was investigated in anesthetized dogs. Hemodynamics, regional myocardial blood flow (MBF (ml/min/g):radioactive microspheres) and the left ventricular transmural distribution of flow (endo/epi) were measured. Intracoronary infusion of Ach (10 and AA (585 significantly (P < .05*) increased myocardial perfusion and selectively redistributed flow to the subendocardium (increased endo/epi) without changes in systemic hemodynamics. Inhibition of phospholipase A/sub 2/ by quinacrine (Q; 600, ic) attenuated the increase in myocardial perfusion produced by Ach but not by AA and inhibited the redistribution of flow to the subendocardium. The present results suggest that endothelium-dependent vasodilators produce a preferential increase in subendocardial perfusion via a product of AA metabolism.

  10. Blood transfusion in preterm infants improves intestinal tissue oxygenation without alteration in blood flow. (United States)

    Banerjee, J; Leung, T S; Aladangady, N


    The objective of the study was to investigate the splanchnic blood flow velocity and oximetry response to blood transfusion in preterm infants according to postnatal age. Preterm infants receiving blood transfusion were recruited to three groups: 1-7 (group 1; n = 20), 8-28 (group 2; n = 21) and ≥29 days of life (group 3; n = 18). Superior mesenteric artery (SMA) peak systolic (PSV) and diastolic velocities were measured 30-60 min pre- and post-transfusion using Doppler ultrasound scan. Splanchnic tissue haemoglobin index (sTHI), tissue oxygenation index (sTOI) and fractional tissue oxygen extraction (sFTOE) were measured from 15-20 min before to post-transfusion using near-infrared spectroscopy. The mean pretransfusion Hb in group 1, 2 and 3 was 11, 10 and 9 g/dl, respectively. The mean (SD) pretransfusion SMA PSV in group 1, 2 and 3 was 0·63 (0·32), 0·81 (0·33) and 0·97 (0·40) m/s, respectively, and this did not change significantly following transfusion. The mean (SD) pretransfusion sTOI in group 1, 2 and 3 was 36·7 (19·3), 44·6 (10·4) and 41·3 (10·4)%, respectively. The sTHI and sTOI increased (P transfusion in all groups. On multivariate analysis, changes in SMA PSV and sTOI following blood transfusion were not associated with PDA, feeding, pretransfusion Hb and mean blood pressure. Pretransfusion baseline splanchnic tissue oximetry and blood flow velocity varied with postnatal age. Blood transfusion improved intestinal tissue oxygenation without altering mesenteric blood flow velocity irrespective of postnatal ages. © 2016 International Society of Blood Transfusion.

  11. Effect of TIPS placement on portal and splanchnic arterial blood flow in 4-dimensional flow MRI

    Energy Technology Data Exchange (ETDEWEB)

    Stankovic, Zoran [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); University Medical Center Freiburg, Department of Diagnostic Radiology and Medical Physics, Freiburg (Germany); Roessle, Martin; Schultheiss, Michael [University Medical Center Freiburg, Department of Gastroenterology, Freiburg (Germany); Euringer, Wulf; Langer, Mathias [University Medical Center Freiburg, Department of Diagnostic Radiology and Medical Physics, Freiburg (Germany); Salem, Riad; Barker, Alex; Carr, James; Collins, Jeremy D. [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); Markl, Michael [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); Northwestern University, Department of Biomedical Engineering, McCormick School of Engineering, Chicago, IL (United States)


    To assess changes in portal and splanchnic arterial haemodynamics in patients undergoing transjugular intrahepatic portosystemic shunt (TIPS) using four-dimensional (4D) flow MRI, a non-invasive, non-contrast imaging technique. Eleven patients undergoing TIPS implantation were enrolled. K-t GRAPPA accelerated non-contrast 4D flow MRI of the liver vasculature was applied with acceleration factor R = 5 at 3Tesla. Flow analysis included three-dimensional (3D) blood flow visualization using time-resolved 3D particle traces and semi-quantitative flow pattern grading. Quantitative evaluation entailed peak velocities and net flows throughout the arterial and portal venous (PV) systems. MRI measurements were taken within 24 h before and 4 weeks after TIPS placement. Three-dimensional flow visualization with 4D flow MRI revealed good image quality with minor limitations in PV flow. Quantitative analysis revealed a significant increase in PV flow (562 ± 373 ml/min before vs. 1831 ± 965 ml/min after TIPS), in the hepatic artery (176 ± 132 ml/min vs. 354 ± 140 ml/min) and combined flow in splenic and superior mesenteric arteries (770 ml/min vs. 1064 ml/min). Shunt-flow assessment demonstrated stenoses in two patients confirmed and treated at TIPS revision. Four-dimensional flow MRI might have the potential to give new information about the effect of TIPS placement on hepatic perfusion. It may explain some unexpected findings in clinical observation studies. (orig.)

  12. Three-dimensional imaging of absolute blood flow velocity and blood vessel position under low blood flow velocity based on Doppler signal information included in scattered light from red blood cells (United States)

    Kyoden, Tomoaki; Akiguchi, Shunsuke; Tajiri, Tomoki; Andoh, Tsugunobu; Hachiga, Tadashi


    The development of a system for in vivo visualization of occluded distal blood vessels for diabetic patients is the main target of our research. We herein describe two-beam multipoint laser Doppler velocimetry (MLDV), which measures the instantaneous multipoint flow velocity and can be used to observe the blood flow velocity in peripheral blood vessels. By including a motorized stage to shift the measurement points horizontally and in the depth direction while measuring the velocity, the path of the blood vessel in the skin could be observed using blood flow velocity in three-dimensional space. The relationship of the signal power density between the blood vessel and the surrounding tissues was shown and helped us identify the position of the blood vessel. Two-beam MLDV can be used to simultaneously determine the absolute blood flow velocity distribution and identify the blood vessel position in skin.

  13. Outcome of splanchnic blood flow determination in patients with suspected chronic intestinal ischaemia. A retrospective survey

    DEFF Research Database (Denmark)

    Møller, Søren; Madsen, Jan Lysgård


    flow: A, normal response (splanchnic blood flow > or = 200 ml/min); B, possible abnormal response (splanchnic blood flow 51-199 ml/min); and C, definitive abnormal response (splanchnic blood flow 50 ml/min). Where surgery took place, the type of operation was noted. RESULTS: Forty patients had...

  14. Sympathetic reflex control of blood flow in human peripheral tissues

    DEFF Research Database (Denmark)

    Henriksen, O


    sympathetic vasoconstrictor reflexes are blocked. Blood flow has been measure by the local 133Xe-technique. The results indicate the presence of spinal as well as supraspinal sympathetic vasoconstrictor reflexes to human peripheral tissues. Especially is emphasized the presence of a local sympathetic veno......Sympathetic vasoconstrictor reflexes are essential for the maintenance of arterial blood pressure in upright position. It has been generally believed that supraspinal sympathetic vasoconstrictor reflexes elicited by changes in baroreceptor activity play an important role. Recent studies on human...

  15. Cerebral blood flow autoregulation in experimental liver failure

    DEFF Research Database (Denmark)

    Dethloff, T.J.; Larsen, F.S.; Knudsen, Gitte Moos


    Patients with acute liver failure (ALF) display impairment of cerebral blood flow (CBF) autoregulation, which may contribute to the development of fatal intracranial hypertension, but the pathophysiological mechanism remains unclear. In this study, we examined whether loss of liver mass causes...... impairment of CBF autoregulation. Four rat models were chosen, each representing different aspects of ALF: galactosamine (GlN) intoxication represented liver necrosis, 90% hepatectomy (PHx90) represented reduction in liver mass, portacaval anastomosis (PCA) represented shunting of blood...... edema/high ICP. Nor does portacaval shunting or hyperammonemia impair autoregulation. Rather, massive liver necrosis and reduced liver mass are associated with loss of CBF autoregulation Udgivelsesdato: 2008/5...

  16. Tomographic cerebral blood flow measurement during carotid surgery

    DEFF Research Database (Denmark)

    Rathenborg, Lisbet Knudsen; Vorstrup, Sidsel; Olsen, K S


    OBJECTIVES: The aim of the study was to depict regional cerebral blood flow (rCBF) during carotid cross clamping using 99mTechnetium-hexamethylpropylene amine oxime (TcHMPAO). This tracer rapidly passes the blood-brain barrier and is retained for hours in the brain tissue. Injecting TcHMPAO during......, Copenhagen, Denmark. MATERIAL: 15 patients who during a period of 4 months underwent carotid endarterectomy. CHIEF OUTCOME MEASURES: Prior to surgery rCBF was determined using 133Xe and SPECT. Intraoperatively stump pressure was measured and a bolus of TcHMPAO was injected for later SPECT measurement. MAIN...

  17. Quantitative flow and velocity measurements of pulsatile blood flow with 4D-DSA (United States)

    Shaughnessy, Gabe; Hoffman, Carson; Schafer, Sebastian; Mistretta, Charles A.; Strother, Charles M.


    Time resolved 3D angiographic data from 4D DSA provides a unique environment to explore physical properties of blood flow. Utilizing the pulsatility of the contrast waveform, the Fourier components can be used to track the waveform motion through vessels. Areas of strong pulsatility are determined through the FFT power spectrum. Using this method, we find an accuracy from 4D-DSA flow measurements within 7.6% and 6.8% RMSE of ICA PCVIPR and phantom flow probe validation measurements, respectively. The availability of velocity and flow information with fast acquisition could provide a more quantitative approach to treatment planning and evaluation in interventional radiology.

  18. Complex blood flow quantification using real-time in vivo vector flow ultrasound

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Per, Haugaard

    A new method to define and quantify complex blood flow is presented. The standard deviations of real-time in vivo vector flow angle estimates are used. Using vector flow ultrasound imaging both carotid bifurcations of two healthy volunteers were scanned. Scanning was performed with a 7.6 MHz linear...... transducer (8670, B-K Medical, Denmark) and a commercial vector flow ultrasound scanner (ProFocus 2202, B-K Medical). Eight video sequences of one cardiac cycle were obtained. In every frame boxes were placed to define the common carotid artery(box1) and the carotid bulb(box2). The standard deviation...

  19. FDM Analysis for Blood Flow through Stenosed Tapered Arteries

    Directory of Open Access Journals (Sweden)

    Sankar DS


    Full Text Available Abstract A computational model is developed to analyze the unsteady flow of blood through stenosed tapered narrow arteries, treating blood as a two-fluid model with the suspension of all the erythrocytes in the core region as Herschel-Bulkley fluid and the plasma in the peripheral layer as Newtonian fluid. The finite difference method is employed to solve the resulting system of nonlinear partial differential equations. The effects of stenosis height, peripheral layer thickness, yield stress, viscosity ratio, angle of tapering and power law index on the velocity, wall shear stress, flow rate and the longitudinal impedance are analyzed. It is found that the velocity and flow rate increase with the increase of the peripheral layer thickness and decrease with the increase of the angle of tapering and depth of the stenosis. It is observed that the flow rate decreases nonlinearly with the increase of the viscosity ratio and yield stress. The estimates of the increase in the longitudinal impedance to flow are considerably lower for the two-fluid Herschel-Bulkley model compared with those of the single-fluid Herschel-Bulkley model. Hence, it is concluded that the presence of the peripheral layer helps in the functioning of the diseased arterial system.

  20. Effect of body position and ventilation on umbilical artery and venous blood flows during delayed umbilical cord clamping in preterm lambs. (United States)

    Hooper, Stuart B; Crossley, Kelly J; Zahra, Valerie A; van Vonderen, Jeroen; Moxham, Alison; Gill, Andrew W; Kluckow, Martin; Te Pas, Arjan B; Wallace, Euan M; Polglase, Graeme R


    While delayed umbilical cord clamping (UCC) is thought to facilitate placental to infant blood transfusion, the physiological factors regulating flow in the umbilical arteries and veins during delayed UCC is unknown. We investigated the effects of gravity, by changing fetal height relative to the placenta, and ventilation on umbilical blood flows and the cardiovascular transition during delayed UCC at birth. Catheters and flow probes were implanted into preterm lambs (128 days) prior to delivery to measure pulmonary, carotid, umbilical artery (UaBF) and umbilical venous (UvBF) blood flows. Lambs were placed either 10 cm below or 10 cm above the ewe. Ventilation commenced 2-3 min before UCC and continued for 30 min after UCC. Gravity reduced umbilical and cerebral flows when lambs were placed below the midline, but the reduction in UaBF and UvBF was similar. Ventilation during delayed UCC reduced UvBF and UaBF by similar amounts, irrespective of the lamb's position, such that flows into and out of the placenta remained balanced. The effects of ventilation on umbilical flows were much greater than the effects of gravity, but no net placental to lamb blood transfusion could be detected under any condition. Cardiovascular parameters, cerebral oxygen kinetics and final blood volumes were similar in both groups 5 min after UCC. Gravity caused small transient effects on umbilical and cerebral flow, but given changes were similar in umbilical arteries and veins, no net placental transfusion was detected. Ventilation during delayed UCC has a markedly greater influence on cardiovascular function in the newborn. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to

  1. Pulsatile blood flow in elastic artery with model aneurysm (United States)

    Nikolov, N.; Radev, St.; Tabakova, S.


    The mathematical modeling and numerical simulations are expected to play an important role to predict the genesis of different cardiovascular diseases, such as the formation and rupture of aneurysms. In the present work, the numerical solutions of the oscillatory blood flow are constructed for an elastic artery with a model aneurysm by use of the software ANSYS. It is observed that the artery elastic strain behaves in a different way: stably or unstably depending on the different combinations between the flow parameter (outlet pressure) and the elastic modulus of the artery wall.

  2. Transfer function analysis for the assessment of cerebral autoregulation using spontaneous oscillations in blood pressure and cerebral blood flow

    NARCIS (Netherlands)

    van den Abeelen, Aisha; Beek, Arenda H.E.A.; Slump, Cornelis H.; Panerai, Ronney B.; Claassen, Jurgen A.H.R.


    Cerebral autoregulation (CA) is a key mechanism to protect the brain against excessive fluctuations in blood pressure (BP) and maintain cerebral blood flow. Analyzing the relationship between spontaneous BP and cerebral blood flow velocity (CBFV) using transfer function analysis is a widely used

  3. Regional blood flow distribution and oxygen metabolism during mesenteric ischemia and congestion. (United States)

    Cruz, Ruy J; Garrido, Alejandra G; Ribeiro, Cristiane M F; Harada, Tomoyuki; Rocha-e-Silva, Mauricio


    Acute mesenteric ischemia is a potentially fatal vascular emergency with mortality rates ranging between 60% and 80%. Several studies have extensively examined the hemodynamic and metabolic effects of superior mesenteric artery occlusion. On the other hand, the cardiocirculatory derangement and the tissue damage induced by intestinal outflow obstruction have not been investigated systematically. For these reasons we decided to assess the initial impact of venous mesenteric occlusion on intestinal blood flow distribution, and correlate these findings with other systemic and regional perfusion markers. Fourteen mongrel dogs were subjected to 45 min of superior mesenteric artery (SMAO) or vein occlusion (SMVO), and observed for 120 min after reperfusion. Systemic hemodynamics were evaluated using Swan-Ganz and arterial catheters. Regional blood flow (ultrasonic flow probes), intestinal O(2)-derived variables, and mesenteric-arterial and tonometric-arterial pCO(2) gradients (D(mv-a)pCO(2) and D(t-a)pCO(2)) were also calculated. SMVO was associated with hypotension and low cardiac output. A significant increase in the regional pCO(2) gradients was also observed in both groups during the ischemic period. After reperfusion, a progressive reduction in D(mv-a)pCO(2) occurred in the SMVO group; however, no improvement in D(t-a)pCO(2) was observed. The histopathologic injury scores were 2.7 +/- 0.5 and 4.8 +/- 0.2 for SMAO and SMVO, respectively. SMV occlusion promoted early and significant hemodynamic and metabolic derangement at systemic and regional levels. Additionally, systemic pCO(2) gradient is not a reliable parameter to evaluate the local intestinal oxygenation. Finally, the D(t-a)pCO(2) correlates with histologic changes during intestinal congestion or ischemia. However, minor histologic changes cannot be detected using this methodology. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  4. Simulation of branching blood flows on parallel computers. (United States)

    Yue, Xue; Hwang, Feng-Nan; Shandas, Robin; Cai, Xiao-Chuan


    We present a fully parallel nonlinearly implicit algorithm for the numerical simulation of some branching blood flow problems, which require efficient and robust solver technologies in order to handle the high nonlinearity and the complex geometry. Parallel processing is necessary because of the large number of mesh points needed to accurately discretize the system of differential equations. In this paper we introduce a parallel Newton-Krylov-Schwarz based implicit method, and software for distributed memory parallel computers, for solving the nonlinear algebraic systems arising from a Q2-Q1 finite element discretization of the incompressible Navier-Stokes equations that we use to model the blood flow in the left anterior descending coronary artery.

  5. Subcutaneous blood flow in early male pattern baldness

    Energy Technology Data Exchange (ETDEWEB)

    Klemp, P.; Peters, K.; Hansted, B.


    The subcutaneous blood flow (SBF) was measured by the /sup 133/Xe washout method in the scalp of 14 patients with early male pattern baldness. Control experiments were performed in 14 normal haired men matched for age. The SBF in the scalp of the normal individuals was about 10 times higher than previously reported SBF values in other anatomical regions. In patients with early male pattern baldness, SBF was 2.6 times lower than the values found in the normal individuals (13.7 +/- 9.6 vs 35.7 +/- 10.5 ml/100 g/min-1). This difference was statistically significant (p much less than 0.001). A reduced nutritive blood flow to the hair follicles might be a significant event in the pathogenesis of early male pattern baldness.

  6. Cerebral autoregulation control of blood flow in the brain

    CERN Document Server

    Payne, Stephen


    This Brief provides a comprehensive introduction to the control of blood flow in the brain. Beginning with the basic physiology of autoregulation, the author goes on to discuss measurement techniques, mathematical models, methods of analysis, and relevant clinical conditions, all within this single volume. The author draws together this disparate field, and lays the groundwork for future research directions. The text gives an up-to-date review of the state of the art in cerebral autoregulation, which is particularly relevant as cerebral autoregulation moves from the laboratory to the bedside. Cerebral Autoregulation will be useful to researchers in the physical sciences such as mathematical biology, medical physics, and biomedical engineering whose work is concerned with the brain. Researchers in the medical sciences and clinicians dealing with the brain and blood flow, as well as industry professionals developing techniques such as ultrasound, MRI, and CT will also find this Brief of interest.

  7. Assessment of maternal cerebral blood flow in patients with preeclampsia


    Mandić Vesna; Miković` Željko; Đukić Milan; Vasiljević Mladenko; Filimonović Dejan; Bogavac Mirjana


    Introduction Systemic vasoconstrktion in preeclamptic patients increases vascular resistance, and is manifested by increased arterial blood flow velocity. The aim of the study is to evaluate if there is a change of Doppler indices in maternal medial cerbral artery (MCA) in severe preeclampsia due to: 1) severity of clinical symptoms, 2) the beginning of eclamptic attack and 3) the application of anticonvidsive therapy. Material and methods A prospective clinical study included 92 pregnant wom...

  8. Feasibility of patient specific aortic blood flow CFD simulation. (United States)

    Svensson, Johan; Gårdhagen, Roland; Heiberg, Einar; Ebbers, Tino; Loyd, Dan; Länne, Toste; Karlsson, Matts


    Patient specific modelling of the blood flow through the human aorta is performed using computational fluid dynamics (CFD) and magnetic resonance imaging (MRI). Velocity patterns are compared between computer simulations and measurements. The workflow includes several steps: MRI measurement to obtain both geometry and velocity, an automatic levelset segmentation followed by meshing of the geometrical model and CFD setup to perform the simulations follwed by the actual simulations. The computational results agree well with the measured data.

  9. The Effect of Insulating Blood Warmer Output Tubing on the Temperature of Packed Red Blood Cells at Low Flow Rates (United States)


    blood cells at the point of patient entry at low flow rates . Utilizing a surgical suite, every attempt was made to replicate a true surgical setting...Flow control pumps were used to regulate flow rates of 300, 600, and 900 milliliters per hour (ml/hr) through Fenwall Laboratories blood warming coils

  10. Splanchnic blood flow and hepatic glucose production in exercising humans

    DEFF Research Database (Denmark)

    Bergeron, R; Kjaer, M; Simonsen, L


    The study examined the implication of the renin-angiotensin system (RAS) in regulation of splanchnic blood flow and glucose production in exercising humans. Subjects cycled for 40 min at 50% maximal O(2) consumption (VO(2 max)) followed by 30 min at 70% VO(2 max) either with [angiotensin-converti......The study examined the implication of the renin-angiotensin system (RAS) in regulation of splanchnic blood flow and glucose production in exercising humans. Subjects cycled for 40 min at 50% maximal O(2) consumption (VO(2 max)) followed by 30 min at 70% VO(2 max) either with [angiotensin......-converting enzyme (ACE) blockade] or without (control) administration of the ACE inhibitor enalapril (10 mg iv). Splanchnic blood flow was estimated by indocyanine green, and splanchnic substrate exchange was determined by the arteriohepatic venous difference. Exercise led to an approximately 20-fold increase (P ... blockade; 0.74 +/- 0.14 l/min, control), whereas splanchnic glucose production (at rest: 0.50 +/- 0.06, ACE blockade; 0.68 +/- 0.10 mmol/min, control) increased during moderate exercise (1.97 +/- 0.29, ACE blockade; 1.91 +/- 0.41 mmol/min, control). Refuting a major role of the RAS for these responses...

  11. Bolus arrival time and cerebral blood flow responses to hypercarbia. (United States)

    Donahue, Manus J; Faraco, Carlos C; Strother, Megan K; Chappell, Michael A; Rane, Swati; Dethrage, Lindsey M; Hendrikse, Jeroen; Siero, Jeroen C W


    The purpose of this study was to evaluate how cerebral blood flow and bolus arrival time (BAT) measures derived from arterial spin labeling (ASL) MRI data change for different hypercarbic gas stimuli. Pseudocontinuous ASL (pCASL) was applied (3.0T; spatial resolution=4 × 4 × 7 mm(3); repetition time/echo time (TR/TE)=3,600/11 ms) sequentially in healthy volunteers (n=12; age=30±4 years) for separate experiments in which (i) normocarbic normoxia (i.e., room air), hypercarbic normoxia (i.e., 5% CO₂/21% O₂/74% N2), and hypercarbic hyperoxia (i.e., carbogen: 5% CO₂/95% O₂) gas was administered (12 L/minute). Cerebral blood flow and BAT changes were quantified using models that account for macrovascular signal and partial volume effects in all gray matter and regionally in cerebellar, temporal, occipital, frontal, and parietal lobes. Regional reductions in BAT of 4.6% to 7.7% and 3.3% to 6.6% were found in response to hypercarbic normoxia and hypercarbic hyperoxia, respectively. Cerebral blood flow increased by 8.2% to 27.8% and 3.5% to 19.8% for hypercarbic normoxia and hypercarbic hyperoxia, respectively. These findings indicate that changes in BAT values may bias functional ASL data and thus should be considered when choosing appropriate experimental parameters in calibrated functional magnetic resonance imaging or ASL cerebrovascular reactivity experiments that use hypercarbic gas stimuli.

  12. Pulsed photoacoustic Doppler flow measurements in blood-mimicking phantoms (United States)

    Brunker, J.; Beard, P.


    The feasibility of making spatially resolved measurements of blood flow using pulsed photoacoustic Doppler techniques has been explored. Doppler time shifts were quantified via cross-correlation of pairs of photoacoustic waveforms generated within a blood-simulating phantom using pairs of laser light pulses. The photoacoustic waves were detected using a focussed or planar PZT ultrasound transducer. For each flow measurement, a series of 100 waveform pairs was collected. Previous data processing methods involved rejection of poorly correlated waveform pairs; the modal velocity value and standard deviation were then extracted from the selected distribution of velocity measurements. However, the data selection criteria used in this approach is to some extent arbitrary. A new data analysis protocol, which involves averaging the 100 cross-correlation functions and thus uses all of the measured data, has been designed in order to prevent exclusion of outliers. This more rigorous approach has proved effective for quantifying the linear motion of micron-scale absorbers imprinted on an acetate sheet moving with velocities in the range 0.14 to 1.25 ms-1. Experimental parameters, such as the time separation between the laser pulses and the transducer frequency response, were evaluated in terms of their effect on the accuracy, resolution and range of measurable velocities. The technique was subsequently applied to fluid phantoms flowing at rates less than 5 mms-1 along an optically transparent tube. Preliminary results are described for three different suspensions of phenolic resin microspheres, and also for whole blood. Velocity information was obtained even under non-optimal conditions using a low frequency transducer and a low pulse repetition frequency. The distinguishing advantage of pulsed rather than continuous-wave excitation is that spatially resolved velocity measurements can be made. This offers the prospect of mapping flow within the microcirculation and thus

  13. Sevoflurane effects on retrobulbar arteries blood flow in children. (United States)

    Geeraerts, T; Devys, J-M; Berges, O; Dureau, P; Plaud, B


    Measure of blood flow velocity in retrobulbar vessels is performed to determine the severity of ophthalmic pathologies as glaucoma. In children, this measure is usually performed under general anaesthesia. Sevoflurane is known to not modify cerebral blow flow velocities. However, its effect on retrobulbar circulation is not known. This study was designed to evaluate the effect of sevoflurane on retrobulbar circulation flow velocity in children undergoing examination for ocular disorders under general anaesthesia. Thirteen mechanically ventilated children (Fi(O2))=1) were included. Blood flow velocities of central retinal artery, ophthalmic artery, and middle cerebral artery were measured by Doppler ultrasound during 1 and 2 age-adjusted minimal alveolar concentration (MAC) sevoflurane anaesthesia. Intra-ocular pressure and non-invasive haemodynamic parameters were also measured. End-tidal carbon dioxide tension was controlled during all the study period. Mean arterial pressure decreased from 1 to 2 age-adjusted MAC sevoflurane (58 [12] vs 54 [12] mm Hg, P=0.01). In the ophthalmic artery, end diastolic velocity (EDV) decreased significantly at 2 MAC (1 MAC: 4.4 [4] cm s(-1) vs 2 MAC: 1.4 [2.4] cm s(-1); P=0.04) and resistivity index (RI) increased significantly (1 MAC: 0.83 [0.11] vs 2 MAC: 0.93 [0.09]; P=0.007). Systolic velocity, EDV, and RI remained constant in the central retinal artery and in the middle cerebral artery. High alveolar concentration of sevoflurane decreased blood flow velocity in the ophthalmic artery, but not in the central retinal and the middle cerebral arteries in children ventilated in hyperoxic condition. This effect was related to a decrease in mean arterial pressure. This vessel-dependent effect may be explained by the different autoregulatory mechanisms of these arteries. In the present hyperoxic conditions, the vascular effect of sevoflurane may have been limited in the central retinal artery and not in the ophthalmic artery.

  14. Nitric oxide and prostaglandins influence local skeletal muscle blood flow during exercise in humans: coupling between local substrate uptake and blood flow

    DEFF Research Database (Denmark)

    Kalliokoski, Kari K; Langberg, Henning; Ryberg, Ann Kathrine


    Synergic action of nitric oxide (NO) and prostaglandins (PG) in the regulation of muscle blood flow during exercise has been demonstrated. In the present study, we investigated whether these vasodilators also regulate local blood flow, flow heterogeneity, and glucose uptake within the exercising...

  15. Mechanical, hormonal and metabolic influences on blood vessels, blood flow and bone. (United States)

    Prisby, Rhonda D


    Bone tissue is highly vascularized due to the various roles bone blood vessels play in bone and bone marrow function. For example, the vascular system is critical for bone development, maintenance and repair and provides O 2 , nutrients, waste elimination, systemic hormones and precursor cells for bone remodeling. Further, bone blood vessels serve as egress and ingress routes for blood and immune cells to and from the bone marrow. It is becoming increasingly clear that the vascular and skeletal systems are intimately linked in metabolic regulation and physiological and pathological processes. This review examines how agents such as mechanical loading, parathyroid hormone, estrogen, vitamin D and calcitonin, all considered anabolic for bone, have tremendous impacts on the bone vasculature. In fact, these agents influence bone blood vessels prior to influencing bone. Further, data reveal strong associations between vasodilator capacity of bone blood vessels and trabecular bone volume, and poor associations between estrogen status and uterine mass and trabecular bone volume. Additionally, this review highlights the importance of the bone microcirculation, particularly the vascular endothelium and NO-mediated signaling, in the regulation of bone blood flow, bone interstitial fluid flow and pressure and the paracrine signaling of bone cells. Finally, the vascular endothelium as a mediator of bone health and disease is considered. © 2017 Society for Endocrinology.

  16. The effect of blood cell count on coronary flow in patients with coronary slow flow phenomenon. (United States)

    Soylu, Korhan; Gulel, Okan; Yucel, Huriye; Yuksel, Serkan; Aksan, Gokhan; Soylu, Ayşegül İdil; Demircan, Sabri; Yılmaz, Ozcan; Sahin, Mahmut


    The coronary slow flow phenomenon (CSFP) is a coronary artery disease with a benign course, but its pathological mechanisms are not yet fully understood.The purpose of this controlled study was to investigate the cellular content of blood in patients diagnosed with CSFP and the relationship of this with coronary flow rates. Selective coronary angiographies of 3368 patients were analyzed to assess Thrombolysis in Myocardial Infarction (TIMI) frame count (TFC) values. Seventy eight of them had CSFP, and their demographic and laboratory findings were compared with 61 patients with normal coronary flow. Patients' demographic characteristics were similar in both groups. Mean corrected TFC (cTFC) values were significantly elevated in CSFP patients (p<0.001). Furthermore, hematocrit and hemoglobin values, and eosinophil and basophil counts of the CSFP patients were significantly elevated compared to the values obtained in the control group (p=0.005, p=0.047, p=0.001 and p=0.002, respectively). The increase observed in hematocrit and eosinophil levels showed significant correlations with increased TFC values (r=0.288 and r=0.217, respectively). Significant changes have been observed in the cellular composition of blood in patients diagnosed with CSFP as compared to the patients with normal coronary blood flow. The increases in hematocrit levels and in the eosinophil and basophil counts may have direct or indirect effects on the rate of coronary blood flow.

  17. Analyzing Circle of Willis blood flow in ischemic stroke patients through 3D Stroke Arterial Flow Estimation. (United States)

    Chien, Aichi; Viñuela, Fernando


    Background The objective of ischemic stroke (IS) treatment is to achieve revascularization in cerebral arteries to restore blood flow. However, there is no available method to extract arterial flow data from clinical CTA images. We developed 3D Stroke Arterial Flow Estimation (SAFE), which provides blood flow data throughout the Circle of Willis based on 3D CTA and allows comparison of arterial flow distribution in the brain. Methods We implemented a newly developed 3D vascular reconstruction algorithm for clinical stroke CTA images. Based on the patient-specific vascular structure, SAFE calculates time-resolved blood flow information for the entire Circle of Willis and allows quantitative flow study of IS cases. Clinical IS cases are presented to demonstrate the feasibility. Four patients with CTA images and CT perfusion data were studied. To validate the SAFE analysis, correlation analysis comparing blood flow at the MCA, ICA, and BA was performed. Results Different blood flow patterns were found in individual IS patients. Altered flow patterns and high collateral flow rates were found near occlusions in all cases. Quantitative comparison of blood flow data showed that SAFE obtained flow data and CTP were significantly correlated and provide complementary information about cerebral blood flow for individual patients. Conclusions We present SAFE analysis for collecting detailed time-resolved cerebral arterial flow data in the entire Circle of Willis for IS. Further study with more cases may be important to test the clinical utilization of SAFE and helpful to the study of the underlying hemodynamics of stroke.

  18. Repeatability of Doppler ultrasonographic measurement of equine digital blood flow. (United States)

    Menzies-Gow, Nicola J; Marr, Celia M


    The repeatability and sensitivity of Doppler ultrasonographic measurement of lateral digital arterial and venous blood flow has not been previously determined. Doppler ultrasonography was used to measure blood flow within the forelimb lateral digital vessels in one normal adult Thoroughbred horse on six occasions and in six normal adult Thoroughbred horses on three occasions, each occasion being at least 1 h apart, to determine the within- and between-horse variation. The values obtained from the right and left lateral digital vessels did not differ significantly. The within-horse coefficients of variation (CV) for arterial and venous measurements were all acceptable ( or = 0.71) for all parameters except venous diameter; the between-horse ICC demonstrated good to excellent repeatability (> or = 0.67) for all parameters except TaVb. Doppler ultrasonography can detect differences of 0.005 and 0.01 ml/ min in digital arterial and venous flow, respectively, using measurements from six horses on three occasions (80% power; P < 0.05). Thus, the technique is sufficiently repeatable and sensitive to be able to detect changes in flow during different physiological or pathological states or following pharmacologic intervention.

  19. Correlation of carotid blood flow and corrected carotid flow time with invasive cardiac output measurements. (United States)

    Ma, Irene W Y; Caplin, Joshua D; Azad, Aftab; Wilson, Christina; Fifer, Michael A; Bagchi, Aranya; Liteplo, Andrew S; Noble, Vicki E


    Non-invasive measures that can accurately estimate cardiac output may help identify volume-responsive patients. This study seeks to compare two non-invasive measures (corrected carotid flow time and carotid blood flow) and their correlations with invasive reference measurements of cardiac output. Consenting adult patients (n = 51) at Massachusetts General Hospital cardiac catheterization laboratory undergoing right heart catheterization between February and April 2016 were included. Carotid ultrasound images were obtained concurrently with cardiac output measurements, obtained by the thermodilution method in the absence of severe tricuspid regurgitation and by the Fick oxygen method otherwise. Corrected carotid flow time was calculated as systole time/√cycle time. Carotid blood flow was calculated as π × (carotid diameter)2/4 × velocity time integral × heart rate. Measurements were obtained using a single carotid waveform and an average of three carotid waveforms for both measures. Single waveform measurements of corrected flow time did not correlate with cardiac output (ρ = 0.25, 95% CI -0.03 to 0.49, p = 0.08), but an average of three waveforms correlated significantly, although weakly (ρ = 0.29, 95% CI 0.02-0.53, p = 0.046). Carotid blood flow measurements correlated moderately with cardiac output regardless of if single waveform or an average of three waveforms were used: ρ = 0.44, 95% CI 0.18-0.63, p = 0.004, and ρ = 0.41, 95% CI 0.16-0.62, p = 0.004, respectively. Carotid blood flow may be a better marker of cardiac output and less subject to measurements issues than corrected carotid flow time.

  20. [Cerebral blood flow assessment of preterm infants during respiratory therapy with the expiratory flow increase technique]. (United States)

    Bassani, Mariana Almada; Caldas, Jamil Pedro Siqueira; Netto, Abimael Aranha; Marba, Sérgio Tadeu Martins


    To assess the impact of respiratory therapy with the expiratory flow increase technique on cerebral hemodynamics of premature newborns. This is an intervention study, which included 40 preterm infants (≤34 weeks) aged 8-15 days of life, clinically stable in ambient air or oxygen catheter use. Children with heart defects, diagnosis of brain lesion and/or those using vasoactive drugs were excluded. Ultrasonographic assessments with transcranial Doppler flowmetry were performed before, during and after the increase in expiratory flow session, which lasted 5minutes. Cerebral blood flow velocity and resistance and pulsatility indices in the pericallosal artery were assessed. Respiratory physical therapy did not significantly alter flow velocity at the systolic peak (p=0.50), the end diastolic flow velocity (p=0.17), the mean flow velocity (p=0.07), the resistance index (p=0.41) and the pulsatility index (p=0.67) over time. The expiratory flow increase technique did not affect cerebral blood flow in clinically-stable preterm infants. Copyright © 2015 Sociedade de Pediatria de São Paulo. Publicado por Elsevier Editora Ltda. All rights reserved.

  1. Cerebral blood flow assessment of preterm infants during respiratory therapy with the expiratory flow increase technique

    Directory of Open Access Journals (Sweden)

    Mariana Almada Bassani


    Full Text Available Abstract Objective: To assess the impact of respiratory therapy with the expiratory flow increase technique on cerebral hemodynamics of premature newborns. Methods: This is an intervention study, which included 40 preterm infants (≤34 weeks aged 8-15 days of life, clinically stable in ambient air or oxygen catheter use. Children with heart defects, diagnosis of brain lesion and/or those using vasoactive drugs were excluded. Ultrasonographic assessments with transcranial Doppler flowmetry were performed before, during and after the increase in expiratory flow session, which lasted 5min. Cerebral blood flow velocity and resistance and pulsatility indices in the pericallosal artery were assessed. Results: Respiratory physical therapy did not significantly alter flow velocity at the systolic peak (p=0.50, the end diastolic flow velocity (p=0.17, the mean flow velocity (p=0.07, the resistance index (p=0.41 and the pulsatility index (p=0.67 over time. Conclusions: The expiratory flow increase technique did not affect cerebral blood flow in clinically-stable preterm infants.

  2. Renal blood flow and metabolism after cold ischaemia

    DEFF Research Database (Denmark)

    Henriksen, J H; Petersen, H K


    .01) immediately after re-established perfusion and 36% (P less than 0.02) 30 min later. In one additional patient, who had a short warm ischaemia (8 min), the flow pattern was the same. As arterial pressure remained constant, the reduced RBF signifies an increased renal vascular resistance. Renal O2-uptake......Peroperative measurements of renal blood flow (RBF), renal O2-uptake, and renal venous lactate/pyruvate (L/P) ratio were performed before and after a period of 30-71 min of hypothermic (10-15 degrees C) renal ischaemia in nine patients, undergoing surgery for renal calculi. Before ischaemia, RBF...... and renal venous L/P ratio were almost constant, indicating no significant anaerobic processes being involved in the flow response. None of the patients showed any signs of reactive hyperaemia. It is concluded that hypothermic renal ischaemia may be followed by an increased renal vascular resistance even...

  3. Occlusion cuff for routine measurement of digital blood pressure and blood flow

    DEFF Research Database (Denmark)

    Lassen, N A; Krähenbühl, B; Hirai, M


    A miniaturized blood pressure cuff made of plastic material and applicable to fingers and toes is described. The cuff was compared to rubber cuffs and to bladder-free cuffs. It was found to be more reliable than the former type and much easier to use than the latter type. It is recommended for us...... in conjunction with a mercury-in-Silastic strain gauge for routine measurement of digital blood pressure and blood flow in patients with arterial disease.......A miniaturized blood pressure cuff made of plastic material and applicable to fingers and toes is described. The cuff was compared to rubber cuffs and to bladder-free cuffs. It was found to be more reliable than the former type and much easier to use than the latter type. It is recommended for use...

  4. Outcome of splanchnic blood flow determination in patients with suspected chronic intestinal ischaemia. A retrospective survey

    DEFF Research Database (Denmark)

    Møller, Søren; Madsen, Jan Lysgård


    flow: A, normal response (splanchnic blood flow > or = 200 ml/min); B, possible abnormal response (splanchnic blood flow 51-199 ml/min); and C, definitive abnormal response (splanchnic blood flow ... a normal meal-induced response, 23 patients had a possible abnormal response and 10 patients had a definitive abnormal response, which gave evidence of chronic intestinal ischaemia. In the total patient population, the increase in splanchnic blood flow was significantly correlated to an increase in hepatic...... oxygen uptake (r = 0.38, P abnormal meal-induced splanchnic blood flow and 30% of these patients...

  5. The effect of glucagon-like peptide-2 on arterial blood flow and cardiac parameters

    DEFF Research Database (Denmark)

    Bremholm, Lasse; Hornum, Mads; Andersen, Ulrik B


    Glucagon-like peptide-2 (GLP-2) is known to increase mesenteric blood flow. The aim of the study was to evaluate the effect of GLP-2 on blood flow in different vascular sites, and dynamic changes in cardiac parameters.......Glucagon-like peptide-2 (GLP-2) is known to increase mesenteric blood flow. The aim of the study was to evaluate the effect of GLP-2 on blood flow in different vascular sites, and dynamic changes in cardiac parameters....


    Directory of Open Access Journals (Sweden)

    H. Mazaher


    Full Text Available Vertebrobasilar insufficiency is the cause of cerebrovascular accidents in 20% of cases. There are few reports regarding spectral Doppler indices (SDIs of vertebral arteries (VAs normal blood flow. The objective of this study was to provide basic reference data about SDIs of VAs normal blood flow separately and in comparison with internal carotid arteries (ICAs and common carotid arteries (CCAs normal blood flows SDIs. This cross-sectional study performed on 70 normal patients. Color Doppler sonography (CDS and spectral Doppler sonography (SDS of right and left VAs (RVA and LVA, right and left CCAs (RCCA and LCCA, right and left ICAs (RICA and LICA, were performed. The mean PSV, EDV, and RI values of RVA blood flow were as 41.60 ± 9.6 cm/s, 14.60 ± 3.7 cm/s and 0.65 ± 0.06, and the mean PSV, EDV and RI values of LVA blood flow were as 42.20 ± 10.2 cm/s, 15.20 ± 4.2 cm/s, and 0.64 ± 0.05, respectively. There was not statistically significant difference between the mean PSV, EDV and RI values of RVA and LVA blood flows. The mean PSV and EDV values of VAs blood flows were significantly lower than the values of CCAs and ICCAs blood flows, respectively. The mean RI value of VAs blood flows was significantly lower than the mean RI Value of CCAs blood flows, but there was not statistically significant difference between the mean RI value of VAs blood flows and the mean RI value of ICAs blood flows.

  7. Heterogeneity of cerebral blood flow: a fractal approach

    Energy Technology Data Exchange (ETDEWEB)

    Kuikka, J.T.; Hartikainen, P. [Department of Clinical Physiology, Kuopioo Univ. Hospital (Finland); Department of Neurology, Kuopio Univ. Hosspital (Finland); Niuvanniemi Hospital, Kuopio (Finland)


    Aim: We demonstrate the heterogeneity of regional cerebral blood flow using a fractal approach and single-photon emission computed tomography (SPECT). Method: Tc-99m-labelled ethylcysteine dimer was injected intravenously in 10 healthy controls and in 10 patients with dementia of frontal lobe type. The head was imaged with a gamma camera and transaxial, sagittal and coronal slices were reconstructed. Two hundred fifty-six symmetrical regions of interest (ROIs) were drawn onto each hemisphere of functioning brain matter. Fractal analysis was used to examine the spatial heterogeneity of blood flow as a function of the number of ROIs. Results: Relative dispersion (=coefficient of variation of the regional flows) was fractal-like in healthy subjects and could be characterized by a fractal dimension of 1.17{+-}0.05 (mean{+-}SD) for the left hemisphere and 1.15{+-}0.04 for the right hemisphere, respectively. The fractal dimension of 1.0 reflects completely homogeneous blood flow and 1.5 indicates a random blood flow distribution. Patients with dementia of frontal lobe type had a significantly lower fractal dimension of 1.04{+-}0.03 than in healthy controls. (orig.) [German] Ziel: Unter Einsatz einer fraktalen Annaeherung und SPECT wird die Heterogenitaet der regionalen Hirndruchblutung demonstriert. Methode: Tc-99m-ECD wurde nach intravenoeser Injektion bei zehn Gesunden sowie bei zehn Patienten mit Demenz vom Frontallappen-Typ eingesetzt. Aus dem SPECT-Umlauf wurden transaxiale, sagittale und koronare Schnitte rekonstruiert. 265 symmetrische Regions of Interest wurden im Gebiet der funktionellen grauen Substanz fuer jede Hemisphaere markiert. Die fraktale Analyse wurde eingesetzt zur Bestimmung der raeumlichen Heterogenitaet der Hirndurchblutung als Funktion der ROI-Anzahl. Ergebnisse: Die relative Streuung (Variationskoeffizient der regionalen Durchblutung) war bei Gesunden fraktalaehnlich geordnet und konnte durch eine Fraktaldimension von 1,17{+-}0,05 (Mittelwert

  8. Resistance exercise with different volumes: blood pressure response and forearm blood flow in the hypertensive elderly

    Directory of Open Access Journals (Sweden)

    Brito AF


    Full Text Available Aline de Freitas Brito,1 Caio Victor Coutinho de Oliveira,2 Maria do Socorro Brasileiro-Santos,1 Amilton da Cruz Santos1 1Physical Education Department, 2Research Laboratory for Physical Training Applied to Performance and Health, Federal University of Paraíba, João Pessoa, Brazil Background: The purpose of this study was to evaluate the effect of two sessions of resistance exercise with different volumes on post-exercise hypotension, forearm blood flow, and forearm vascular resistance in hypertensive elderly subjects.Methods: The study was conducted with ten hypertensive elderly (65±3 years, 28.7±3 kg/m2 subjected to three experimental sessions, ie, a control session, exercise with a set (S1, and exercise with three sets (S3. For each session, the subjects were evaluated before and after intervention. In the pre-intervention period, blood pressure, forearm blood flow, and forearm vascular resistance were measured after 10 minutes of rest in the supine position. Thereafter, the subjects were taken to the gym to perform their exercise sessions or remained at rest during the same time period. Both S1 and S3 comprised a set of ten repetitions of ten exercises, with an interval of 90 seconds between exercises. Subsequently, the measurements were again performed at 10, 30, 50, 70, and 90 minutes of recovery (post-intervention in the supine position.Results: Post-exercise hypotension was greater in S3 than in S1 (systolic blood pressure, −26.5±4.2 mmHg versus −17.9±4.7 mmHg; diastolic blood pressure, −13.8±4.9 mmHg versus −7.7±5 mmHg, P<0.05. Similarly, forearm blood flow and forearm vascular resistance changed significantly in both sessions with an increase and decrease, respectively, that was more evident in S3 than in S1 (P<0.05.Conclusion: Resistance exercises with higher volume were more effective in causing post-exercise hypotension, being accompanied by an increase in forearm blood flow and a reduction of forearm vascular

  9. Impact of extracorporeal blood flow rate on blood pressure, pulse rate and cardiac output during haemodialysis

    DEFF Research Database (Denmark)

    Schytz, Philip Andreas; Mace, Maria Lerche; Soja, Anne Merete Boas


    BACKGROUND: If blood pressure (BP) falls during haemodialysis (HD) [intradialytic hypotension (IDH)] a common clinical practice is to reduce the extracorporeal blood flow rate (EBFR). Consequently the efficacy of the HD (Kt/V) is reduced. However, only very limited knowledge on the effect......L/min diastolic BP, mean arterial pressure, PR and CO remained unchanged. CONCLUSION: Our study does not show any consistent trend in BP changes by a reduction in EBFR. Reduction in EBFR if BP falls during IDH is thus not supported. However, none of the patients experienced IDH. Further studies are required...... to evaluate the impact of changes in EBFR on BP during IDH....

  10. Age and gender related differences in aortic blood flow

    DEFF Research Database (Denmark)

    Traberg, Marie Sand; Pedersen, Mads Møller; Hemmsen, Martin Christian


    is to investigate the blood flow pat- terns within a group of healthy volunteers (4 females, 7 males) aged 23 to 76 years to identify changes and differences related to age and gender. The healthy volunteers were categorized by gender (male/female) and age (below/above 35 years). Subject-specific flow and geometry...... data were acquired using the research interface on a medical ultrasound scanner and segmentation of 3D magnetic resonance angiography respectively. The largest average diameter was among the elderly males (19.7 (± 1.33) mm) and smallest among the young females (12.4 (± 0.605) mm). The highest peak...... systolic velocity was in the young female group (1.02 (± 0.336) m/s) and lowest in the elderly male group (0.836 (± 0.127) m/s). A geometrical change with age was observed as the AA becomes more bended with age. This also affects the blood flow velocity patterns, which are markedly different from young...

  11. Three-dimensional diastolic blood flow in the left ventricle. (United States)

    Khalafvand, Seyed Saeid; Ng, Eddie Yin-Kwee; Zhong, Liang; Hung, Tin-Kan


    Three-dimensional blood flow in a human left ventricle is studied via a computational analysis with magnetic resonance imaging of the cardiac motion. Formation, growth and decay of vortices during the myocardial dilation are analyzed with flow patterns on various diametric planes. They are dominated by momentum transfer during flow acceleration and deceleration through the mitral orifice. The posterior and anterior vortices form an asymmetric annular vortex at the mitral orifice, providing a smooth transition for the rapid inflow to the ventricle. The development of core vortex accommodates momentum for deceleration and for acceleration at end diastolic atrial contraction. The rate of energy dissipation and that of work done by viscous stresses are small; they are approximately balanced with each other. The kinetic energy flux and the rate of work done by pressure delivered to blood from ventricular dilation is well balanced by the total energy influx at the mitral orifice and the rate change of kinetic energy in the ventricle. Published by Elsevier Ltd.

  12. Retinal blood flow measurements and neuroretinal rim damage in glaucoma (United States)

    Logan, J F J; Rankin, S J A; Jackson, A J


    Aim: To assess retinal blood flow characteristics in subjects with normal tension glaucoma (NTG), primary open angle glaucoma (POAG), and a group of controls using the Heidelberg retina flowmeter (HRF). The vascular parameters were correlated against structural damage of the optic nerve head, assessed using the Heidelberg retina tomograph (HRT). Methods: HRF images were obtained in 76 subjects with NTG, 58 with POAG, and 38 controls. Optic nerve head images, acquired using the HRT, were analysed with Moorfields Regression Analysis software. The HRF variables, measured adjacent to a rim segment identified as “abnormal,” were compared with the vascular parameters of the “normal” rim segments. The HRF parameters of the segments identified as normal in glaucoma subjects were compared with matched control segments. Results: The glaucoma subjects had significantly lower retinal haemodynamics than the control subjects. There were no significant differences in the HRF parameters between the NTG and POAG subjects. The discs that had been identified as having abnormal segments had lower HRF values than those with a corresponding normal segment. The glaucoma subjects with normal rim segments had statistically significant lower velocity, flow, and volume measurements than the controls for each location sampled. Conclusion: This study shows a relation between structural damage of the optic nerve head and the level of retinal blood flow. The changes in the circulation could indicate that it may be an early marker of the pathological process. PMID:15258023

  13. Intracoronary ghrelin infusion decreases coronary blood flow in anesthetized pigs. (United States)

    Grossini, Elena; Molinari, Claudio; Mary, David A S G; Ghigo, Ezio; Bona, Gianni; Vacca, Giovanni


    The peptide ghrelin has been linked to the atherosclerotic process and coronary artery disease. We planned to study, for the first time, the primary effects of ghrelin on the intact coronary circulation and determine the mechanisms involved. In 24 sodium pentobarbitone-anesthetized pigs, changes in anterior descending coronary blood flow caused by intracoronary infusion of ghrelin at constant heart rate and arterial pressure were assessed using electromagnetic flowmeters. In 20 pigs, intracoronary infusion of ghrelin decreased coronary blood flow without affecting left ventricular maximum rate of change of left ventricular systolic pressure (dP/dt(max)), filling pressures of the heart or plasma levels of GH. In four pigs, this decrease was graded by step increments of infused dose of the hormone. The mechanisms of the above response were studied in the 20 pigs by repeating the experiment after coronary flow had returned to the control values observed before infusion. The ghrelin-induced coronary vasoconstriction was not affected by iv atropine (five pigs) or phentolamine (five pigs). This response was abolished by iv butoxamine (five pigs) and intracoronary N(omega)-nitro-l-arginine methyl ester (five pigs), even after reversing the increase in arterial pressure and coronary vascular resistance caused by the two blocking agents with iv infusion of papaverine. The present study showed that intracoronary infusion of ghrelin primarily caused coronary vasoconstriction. The mechanisms of this response were shown to involve the inhibition of a vasodilatory beta(2)-adrenergic receptor-mediated effect related to the release of nitric oxide.

  14. Usefulness of measurement of blood flow by RI plethysmography

    Energy Technology Data Exchange (ETDEWEB)

    Kawakami, Kenji; Ling, Qing Cheng; Mori, Yutaka; Tanaka, Uzuru; Shimada, Takao [Jikei Univ., Tokyo (Japan). School of Medicine


    We have developed the RI plethysmography, and have applied it to ordinary clinic diagnosis and the evaluation of treatment. The subjects were 58 cases (39 cases of the obstruction of the peripheral blood circulation: ASO 24 cases, TAO 4 cases and arterial sclerotic change 11 cases; the non-abnormal control was 19 cases). The clinical benefit of this method was evaluated. In the cases with 1 and 2 degrees of Fontaine`s classification and ASO and TAO, the blood flow of legs measured by our method significantly decreased in association with symptoms and angiographic findings. This method is suitable to the determination of angiography and evaluation of the effect of treatment. (author)

  15. Computational fluid dynamics using in vivo ultrasound blood flow measurements

    DEFF Research Database (Denmark)

    Traberg, Marie Sand; Pedersen, Mads Møller; Hemmsen, Martin Christian


    This paper presents a model environment for construction of patient-specific computational fluid dynamic (CFD) models for the abdominal aorta (AA). Realistic pulsatile velocity waveforms are employed by using in vivo ultrasound blood flow measurements. Ultrasound is suitable for acquisition....... The estimated and smoothed velocity profiles were quantitatively compared. The energy contained in the velocity profile after smoothing is 65% larger relative to the noise contaminated estimated profiles. In conclusion, a model environment that produces realistic patient-specific CFD simulation models without...

  16. Elementary wave interactions in blood flow through artery (United States)

    Raja Sekhar, T.; Minhajul


    In this paper, we consider the Riemann problem and interaction of elementary waves for the quasilinear hyperbolic system of conservation laws that arises in blood flow through arteries. We study the properties of solution involving shocks and rarefaction waves and establish the existence and uniqueness conditions. We show that the Riemann problem is solvable for arbitrary initial data under certain condition and construct the condition for no-feasible solution. Finally, we present numerical examples with different initial data and discuss all possible interactions of elementary waves.

  17. Metabolic control of muscle blood flow during exercise in humans

    DEFF Research Database (Denmark)

    Boushel, Robert Christopher


    to exert control of muscle vasodilation. Adenosine, nitric oxide (NO), prostacyclin (PGI2), and endothelial-derived hyperpolarization factor (EDHF) are possible mediators of muscle vasodilation during exercise. In humans, adenosine has been shown to contribute to functional hyperemia as blood flow...... that combined blockade of NOS and PGI2, and NOS and cytochrome P450, both attenuate exercise-induced hyperemia in humans. Combined vasodilator blockade studies offer the potential to uncover important interactions and compensatory vasodilator responses. The signaling pathways that link metabolic events evoked...

  18. Dynamics of renal blood flow autoregulation in rats

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H; Wagner, A J; Marsh, D J


    component most likely represents an intrinsic vascular, myogenic, mechanism. The gain maximum of the admittance in the frequency range corresponding to the autonomous tubular oscillations indicates that the dynamic characteristics responsible for the occurrence of the spontaneous tubular oscillations must......Two separate components could be resolved in tests of the dynamic autoregulation of renal blood flow. The slow component corresponds to the frequency at which spontaneous proximal tubular pressure oscillations are found, and are most likely due to the operation of the TGF. The high frequency...

  19. Validation of Blood Flow Simulations in Intracranial Aneurysms (United States)

    Yu, Yue; Anor, Tomer; Baek, Hyoungsu; Jayaraman, Mahesh; Madsen, Joseph; Karniadakis, George


    Catheter-based digital subtraction angiography (DSA) is the most accurate diagnostic procedure for investigating vascular anomalies and cerebral blood flow. Here we describe utilization of DSA in a patient with an intracranial aneursysm to validate corresponding spectral element simulations. Subsequently, we examine via visualization the structure of flow in internal carotid arteries laden with three different types of aneurysms: (1) a wide-necked saccular aneurysm, (2) a narrower-necked saccular aneurysm, and (3) a case with two adjacent saccular aneurysms. We have found through high resolution simulations that in cases (1) and (3) in physiological conditions a hydrodynamic instability occurs during the decelerating systolic phase resulting in a high frequency oscillation (20-50 Hz). We use the in-silico dye visualization to discriminate among different physical mechanisms causing the instability and contrast their effect with case (2) for which an instability arises only at much higher flowrates.

  20. Skin temperature and subcutaneous adipose blood flow in man

    DEFF Research Database (Denmark)

    Astrup, A; Bülow, J; Madsen, J


    The abdominal subcutaneous adipose tissue blood flow (ATBF) was measured bilaterally by the 133Xe washout method. At one side of the skin (epicutaneous) temperature was varied with a temperature blanket, the other side served as control. There was a significant (P less than 0.001) positive...... correlation between skin temperature and ATBF. In the range from 25 to 37 degrees CATBF increased 9% of the control flow on average per centigrade increase in skin temperature. ATBF at the control side was uninfluenced by the contralateral variations in skin temperature. Although no better correlation could...... be demonstrated between ATBF and subcutaneous temperature than between ATBF and skin temperature, arguments are presented in favour of the hypothesis that ATBF is influenced by the subcutaneous temperature rather than via reflexes from the skin. Infiltration of the 133Xe depots with 20 microgram histamine...

  1. Prioritizing blood flow: cardiovascular performance in response to the competing demands of locomotion and digestion for the Burmese python, Python molurus. (United States)

    Secor, Stephen M; White, Scott E


    Individually, the metabolic demands of digestion or movement can be fully supported by elevations in cardiovascular performance, but when occurring simultaneously, vascular perfusion may have to be prioritized to either the gut or skeletal muscles. Burmese pythons (Python molurus) experience similar increases in metabolic rate during the digestion of a meal as they do while crawling, hence each would have an equal demand for vascular supply when these two actions are combined. To determine, for the Burmese python, whether blood flow is prioritized when snakes are digesting and moving, we examined changes in cardiac performance and blood flow in response to digestion, movement, and the combination of digestion and movement. We used perivascular blood flow probes to measure blood flow through the left carotid artery, dorsal aorta, superior mesenteric artery and hepatic portal vein, and to calculate cardiac output, heart rate and stroke volume. Fasted pythons while crawling experienced a 2.7- and 3.3-fold increase, respectively, in heart rate and cardiac output, and a 66% decrease in superior mesenteric flow. During the digestion of a rodent meal equaling in mass to 24.7% of the snake's body mass, heart rate and cardiac output increased by 3.3- and 4.4-fold, respectively. Digestion also resulted in respective 11.6- and 14.1-fold increases in superior mesenteric and hepatic portal flow. When crawling while digesting, cardiac output and dorsal aorta flow increased by only 21% and 9%, respectively, a modest increase compared with that when they start to crawl on an empty stomach. Crawling did triggered a significant reduction in blood flow to the digesting gut, decreasing superior mesenteric and hepatic portal flow by 81% and 47%, respectively. When faced with the dual demands of digestion and crawling, Burmese pythons prioritize blood flow, apparently diverting visceral supply to the axial muscles.

  2. Endoscopic digital holography for measuring flows in opaque vessels (United States)

    Arévalo, Laura; Palero, Virginia; Lobera, Julia; Arroyo, M. Pilar


    In this work a new application of digital holography for the study of cardio vascular diseases is proposed. The simultaneous measurement of the blood flow velocity and the vein wall deformation can be obtained by combining digital holography and endoscopy. Endoscopes are used for the illumination and recording of digital holograms inside a vein model. Two different endoscopes have been used in different vein models in order to test the technique performance. Preliminary results of flow velocity and wall deformation are presented.

  3. Effects of exercise training with blood flow restriction on blood pressure in medicated hypertensive patients

    Directory of Open Access Journals (Sweden)

    Marcos Antônio Cezar


    Full Text Available Abstract The development of non-pharmacological approaches to hypertension (HA is critical for both prevention and treatment. This study examined the hemodynamic and biochemical responses of medicated hypertensive women to resistance exercise with blood flow restriction (vascular occlusion. Twenty-three women were randomly assigned to one of three groups: High intensity strength training (n = 8; low-intensity resistance exercise with occlusion (n = 8; and control (n = 7. The first two groups underwent eight weeks of training performed twice a week, including three series of wrist flexion exercises with or without vascular occlusion. The exercised with occlusion group showed pre- to post-test reduction in systolic and diastolic blood pressure, mean arterial pressure, and double product, whereas the other groups showed no significant hemodynamic changes. In conclusion, resistance exercise during 8 weeks was effective in lowering blood pressure in medicated hypertensive subjects.

  4. Blood Flow Velocity in Brachial and Subclavian Vessels Immediately After Compressive Procedures for Treatment of Postcancer Therapy Lymphedema in Breast Cancer: A Randomized Blind Clinical Trial. (United States)

    Rezende, Monique Silva; Marsengo, Ana Luiza; de Jesus Guirro, Rinaldo Roberto; de Oliveira Guirro, Elaine Caldeira


    This study sought to evaluate the effect of elastic compression, functional compressive bandaging, and kinesiotherapy on blood flow of the upper limb with lymphedema secondary to the treatment of breast cancer. This was a randomized blind crossover clinical trial with a washout period of 7 days between treatments. We evaluated 20 women with a mean age of 66.85 years (standard deviation = 11.76), undergoing three types of therapeutic procedures randomly applied by lot: kinesiotherapy, functional compressive bandaging + kinesiotherapy (FCB), and elastic compression + kinesiotherapy (EC). Blood flow, including mean and maximum velocity, was assessed by Doppler ultrasound before and after the therapeutic procedure (immediately after, 15 minutes, and 30 minutes). We used two-way analysis of variance for repeated measures followed by Bonferroni's test, considering a significance level of 5%. The EC and FCB groups showed a significant increase in the mean velocity of blood flow in the axillary and brachial arteries and veins compared to the group that received only kinesiotherapy (p  0.05). Moreover, the EC and FCB groups showed greater increase in maximum velocity of blood flow in the brachial artery (p  0.05). Elastic compression and functional compressive bandaging combined with kinesiotherapy increased blood flow of upper limb lymphedema.

  5. [Pulmonary blood flow distribution in acute viral bronchiolitis]. (United States)

    Carvalho, Paulo R A; Cunha, Renato D; Barreto, Sérgio S Menna


    To assess lung perfusion patterns in inpatients with acute viral bronchiolitis using quantitative 99mTc-MAA scintigraphy so as to establish an association with clinical and radiological findings. A comparative, prospective case series study with a focus on diagnosis was carried out in a population of patients with acute viral bronchiolitis admitted to Hospital de Clínicas de Porto Alegre. Inclusion criteria were age between 1 and 24 months and first sudden-onset wheezing episode, suggesting bronchiolitis. The patients in the study were submitted to clinical, radiological and 99mTc-MAA lung perfusion evaluation during the first 24 hours of admission. Statistical analysis employed t test, taking into consideration a significance level of 0.05. The regional distribution of lung blood flow in the 38 patients studied was more pronounced in the upper section of the left lung in relation to the right lung (P1.0 in the upper and middle sections of both lungs. In the lower section it was >1.0 only in the right lung (Pbronchiolitis; only a tendency to redirect lung blood flow towards upper lung sections was observed.

  6. Alterations of Regional Cerebral Blood Flow in Major Depressive Disorder

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Won Hyoung; Chung, Yong An; Seo, Ye Young; Yoo, Ik Dong; Na, Sae Jung; Jung, Hyun Suk; Kim, Ki Jun [College of Medicine, The Catholic University of Korea, Seoul (Korea, Republic of)


    The authors analyzed how the regional cerebral blood flow (rCBF) findings of patients with major depression differ from the normal control, and our results were compared to previous reports. Twelve patients fulfilling DSM-IV criteria for major depression who were off all psychotropic medications for > 4 weeks (male: 7, female: 5, age range: 19approx52 years, average age: 29.3+-9.9 years) and 14 normal volunteers (male: 8, female: 6, age range: 19approx53 years, average age: 31.4+-9.2 years) were recruited. Images of brain perfusion SPECT were obtained using Tc-99m ECD and patterns of the rCBF were compared between patients with major depression and the healthy control subjects. The patients with major depression showed increase of the r-CBF in right lingual gyrus, right fusiform gyrus, left lingual gyrus, left precuneus, and left superior temporal gyrus, and showed decrease of r-CBF in right pons, left medial frontal gyrus, cingulate gyrus of left limbic lobe, cingulate gyrus of right frontal lobe, and cingulate gyrus of right limbic lobe compared to the normal control. The Tc-99m ECD brain perfusion SPECT findings in our study did not differ from the previously reported regional cerebral blood flow pattern of patients with major depression. Especially, decreased rCBF pattern typical to major depression patients in the right pons, left medial frontal gyrus, and cingulate regions was clearly demonstrated

  7. History of International Society for Cerebral Blood Flow and Metabolism. (United States)

    Paulson, Olaf B; Kanno, Iwao; Reivich, Martin; Sokoloff, Louis


    Interest in the brain's circulation dates back more than a century and has been steadily growing. Quantitative methods for measurements of cerebral blood flow (CBF) and energy metabolism became available in the middle of the 20th century and gave a new boost to the research. Scientific meetings dealing with CBF and metabolism were arranged, and the fast growing research led to a demand for a specialized journal. In this scientific environment, the International Society for Cerebral Blood Flow and Metabolism (ISCBFM) and its official Journal of Cerebral Metabolism were established in 1981 and has since then been a major success. The development of new brain imaging methods has had a major impact. Regulation of CBF and ischemia has been the main topics at the meetings. A new field of brain mapping research emerged and has now its own society and meetings. Brain emission tomography research has grown within the society and is now an integrated part. The ISCBFM is a sound society, and support of young scientists is among its goals. Several awards have been established. Other activities including summer schools, courses, satellite meetings, and Gordon conferences have contributed to the success of the society and strengthened the research.

  8. Monitoring blood flow and photobleaching during topical ALA PDT treatment (United States)

    Sands, Theresa L.; Sunar, Ulas; Foster, Thomas H.; Oseroff, Allan R.


    Photodynamic therapy (PDT) using topical aminolevulinic acid (ALA) is currently used as a clinical treatment for nonmelanoma skin cancers. In order to optimize PDT treatment, vascular shutdown early in treatment must be identified and prevented. This is especially important for topical ALA PDT where vascular shutdown is only temporary and is not a primary method of cell death. Shutdown in vasculature would limit the delivery of oxygen which is necessary for effective PDT treatment. Diffuse correlation spectroscopy (DCS) was used to monitor relative blood flow changes in Balb/C mice undergoing PDT at fluence rates of 10mW/cm2 and 75mW/cm2 for colon-26 tumors implanted intradermally. DCS is a preferable method to monitor the blood flow during PDT of lesions due to its ability to be used noninvasively throughout treatment, returning data from differing depths of tissue. Photobleaching of the photosensitizer was also monitored during treatment as an indirect manner of monitoring singlet oxygen production. In this paper, we show the conditions that cause vascular shutdown in our tumor model and its effects on the photobleaching rate.

  9. Adipose tissue and skeletal muscle blood flow during mental stress

    Energy Technology Data Exchange (ETDEWEB)

    Linde, B.; Hjemdahl, P.; Freyschuss, U.; Juhlin-Dannfelt, A.


    Mental stress (a modified Stroop color word conflict test (CWT)) increased adipose tissue blood flow (ATBF; 133Xe clearance) by 70% and reduced adipose tissue vascular resistance (ATR) by 25% in healthy male volunteers. The vasculatures of adipose tissue (abdomen as well as thigh), skeletal muscle of the calf (133Xe clearance), and the entire calf (venous occlusion plethysmography) responded similarly. Arterial epinephrine (Epi) and glycerol levels were approximately doubled by stress. Beta-Blockade by metoprolol (beta 1-selective) or propranolol (nonselective) attenuated CWT-induced tachycardia similarly. Metoprolol attenuated stress-induced vasodilation in the calf and tended to do so in adipose tissue. Propranolol abolished vasodilation in the calf and resulted in vasoconstriction during CWT in adipose tissue. Decreases in ATR, but not in skeletal muscle or calf vascular resistances, were correlated to increases in arterial plasma glycerol (r = -0.42, P less than 0.05), whereas decreases in skeletal muscle and calf vascular resistances, but not in ATR, were correlated to increases in arterial Epi levels (r = -0.69, P less than 0.01; and r = -0.43, P less than 0.05, respectively). The results suggest that mental stress increases nutritive blood flow in adipose tissue and skeletal muscle considerably, both through the elevation of perfusion pressure and via vasodilatation. Withdrawal of vasoconstrictor nerve activity, vascular beta 2-adrenoceptor stimulation by circulating Epi, and metabolic mechanisms (in adipose tissue) may contribute to the vasodilatation.

  10. Multiscale modeling and simulation of brain blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Perdikaris, Paris, E-mail: [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Grinberg, Leopold, E-mail: [IBM T.J Watson Research Center, 1 Rogers St, Cambridge, Massachusetts 02142 (United States); Karniadakis, George Em, E-mail: [Division of Applied Mathematics, Brown University, Providence, Rhode Island 02912 (United States)


    The aim of this work is to present an overview of recent advances in multi-scale modeling of brain blood flow. In particular, we present some approaches that enable the in silico study of multi-scale and multi-physics phenomena in the cerebral vasculature. We discuss the formulation of continuum and atomistic modeling approaches, present a consistent framework for their concurrent coupling, and list some of the challenges that one needs to overcome in achieving a seamless and scalable integration of heterogeneous numerical solvers. The effectiveness of the proposed framework is demonstrated in a realistic case involving modeling the thrombus formation process taking place on the wall of a patient-specific cerebral aneurysm. This highlights the ability of multi-scale algorithms to resolve important biophysical processes that span several spatial and temporal scales, potentially yielding new insight into the key aspects of brain blood flow in health and disease. Finally, we discuss open questions in multi-scale modeling and emerging topics of future research.

  11. Thrombospondin 1 and Vasoactive Agents Indirectly Alter Tumor Blood Flow

    Directory of Open Access Journals (Sweden)

    Jeff S. Isenberg


    Full Text Available Nitric oxide (NO plays important physiological roles in the vasculature to regulate angiogenesis, blood flow, and hemostasis. In solid tumors, NO is generally acknowledged to mediate angiogenic responses to several growth factors. This contrasts with conflicting evidence that NO can acutely increase tumor perfusion through local vasodilation or diminish perfusion by preferential relaxation of peripheral vascular beds outside the tumor. Because thrombospondin 1 (TSP1 is an important physiological antagonist of NO in vascular cells, we examined whether, in addition to inhibiting tumor angiogenesis, TSP1 can acutely regulate tumor blood flow. We assessed this activity of TSP1 in the context of perfusion responses to NO as a vasodilator and epinephrine as a vasoconstrictor. Nitric oxide treatment of wild type and TSP1 null mice decreased perfusion of a syngeneic melanoma, whereas epinephrine transiently increased tumor perfusion. Acute vasoactive responses were also independent of the level of tumor-expressed TSP1 in a melanoma xenograft, but recovery of basal perfusion was modulated by TSP1 expression. In contrast, overexpression of truncated TSP1 lacking part of its CD47 binding domain lacked this modulating activity. These data indicate that TSP1 primarily regulates long-term vascular responses in tumors, in part, because the tumor vasculature has a limited capacity to acutely respond to vasoactive agents.

  12. Clustering of microscopic particles in constricted blood flow (United States)

    Bächer, Christian; Schrack, Lukas; Gekle, Stephan


    A mixed suspension of red blood cells (RBCs) and microparticles flows through a cylindrical channel with a constriction mimicking a stenosed blood vessel. Our three-dimensional Lattice-Boltzmann simulations show that the RBCs are depleted right ahead of and after the constriction. Although the RBC mean concentration (hematocrit) is 16.5% or 23.7%, their axial concentration profile is very similar to that of isolated tracer particles flowing along the central axis. Most importantly, however, we find that the stiff microparticles exhibit the opposite behavior. Arriving on a marginated position near the channel wall, they can pass through the constriction only if they find a suitable gap to dip into the dense plug of RBCs occupying the channel center. This leads to a prolonged dwell time and, as a consequence, to a pronounced increase in microparticle concentration right in front of the constriction. For biochemically active particles such as drug delivery agents or activated platelets this clustering may have important physiological consequences, e.g., for the formation of microthrombi.

  13. Screening for ochratoxin A in blood by flow injection analysis. (United States)

    Hult, K; Fuchs, R; Peraica, M; Plestina, R; Ceović, S


    A micromethod for ochratoxin A detection in human sera by flow injection technique is described. The method requires 50 microliter of sera, and it is designed to distinguish samples containing less than 10 ng ochratoxin A per ml. The method is based on fluorescence measurement following a simple extraction procedure for which very small amounts of chemicals are needed. Since the method is not confirmatory, all samples showing fluorescence above a certain intensity have to be reanalysed with some other method where a confirmation step in included. Because of the small amount of serum needed and the rapid procedure (less than 15 min), a large number of samples can be analysed very quickly. The method may therefore be applicable for large screening campaigns conducted to determine the presence of ochratoxin A in blood. This conclusion is based on 1675 samples and 147 standards analysed concurrently by the flow injection technique and an earlier published enzymic method. The method is also suitable for monitoring ochratoxin A levels in the blood of experimental animals.

  14. Endovascular vein harvest: systemic carbon dioxide absorption. (United States)

    Maslow, Andrew M; Schwartz, Carl S; Bert, Arthur; Hurlburt, Peter; Gough, Jeffrey; Stearns, Gary; Singh, Arun K


    Endovascular vein harvest (EDVH) requires CO(2) insufflation to expand the subcutaneous space, allowing visualization and dissection of the saphenous vein. The purpose of this study was to assess the extent of CO(2) absorption during EDVH. Prospective observational study. Single tertiary care hospital. Sixty patients (30 EDVH and 30 open-vein harvest) undergoing isolated coronary artery bypass graft surgery. Hemodynamic, procedural, and laboratory data were collected prior to (baseline), during, and at it the conclusion (final) of vein harvesting. Data were also collected during cardiopulmonary bypass (CPB). Data were compared by using t tests, analysis of variance, and correlation statistics when needed. There were significant increases in arterial CO(2) (PaCO(2), 35%) and decreases in pH (1.35%) during EDVH. These were associated with increases in heart rate, mean blood pressure, and cardiac output. Within the EDVH group, greater elevations (>10 mmHg) in PaCO2 were more likely during difficult harvest procedures, and these patients exhibited greater increase in heart rate. Elevated CO(2) persisted during CPB, requiring higher systemic gas flows and greater use of phenylephrine to maintain desired hemodynamics. EDVH was associated with systemic absorption of CO(2). Greater absorption was more likely in difficult procedures and was associated with greater hemodynamic changes requiring medical therapy.

  15. Integrated Lateral Flow Device for Flow Control with Blood Separation and Biosensing

    Directory of Open Access Journals (Sweden)

    Veronica Betancur


    Full Text Available Lateral flow devices are versatile and serve a wide variety of purposes, including medical, agricultural, environmental, and military applications. Yet, the most promising opportunities of these devices for diagnosis might reside in point-of-care (POC applications. Disposable paper-based lateral flow strips have been of particular interest, because they utilize low-cost materials and do not require expensive fabrication instruments. However, there are constraints on tuning flow rates and immunoassays functionalization in papers, as well as technical challenges in sensors’ integration and concentration units for low-abundant molecular detection. In the present work, we demonstrated an integrated lateral flow device that applied the capillary forces with functionalized polymer-based microfluidics as a strategy to realize a portable, simplified, and self-powered lateral flow device (LFD. The polydimethylsiloxane (PDMS surface was rendered hydrophilic via functionalization with different concentrations of Pluronic F127. Controlled flow is a key variable for immunoassay-based applications for providing enough time for protein binding to antibodies. The flow rate of the integrated LFD was regulated by the combination of multiple factors, including Pluronic F127 functionalized surface properties and surface treatments of microchannels, resistance of the integrated flow resistor, the dimensions of the microstructures and the spacing between them in the capillary pump, the contact angles, and viscosity of the fluids. Various plasma flow rates were regulated and achieved in the whole device. The LFD combined the ability to separate high quality plasma from human whole blood by using a highly asymmetric plasma separation membrane, and created controlled and steady fluid flow using capillary forces produced by the interfacial tensions. Biomarker immunoglobulin G (IgG detection from plasma was demonstrated with a graphene nanoelectronic sensor integrated

  16. Blood pressure and vascular dysfunction underlie elevated cerebral blood flow in systemic lupus erythematosus. (United States)

    Gasparovic, Charles; Qualls, Clifford; Greene, Ernest R; Sibbitt, Wilmer L; Roldan, Carlos A


    In previous studies cerebral blood flow (CBF) was found to be altered in patients with systemic lupus erythematosus (SLE) compared to controls. We investigated the relationships between CBF and clinical data from subjects with SLE with the aim of determining the pathologic factors underlying altered CBF in SLE. A total of 42 SLE subjects and 19 age- and sex-matched healthy control subjects were studied. Dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) was used to measure CBF. Patients and controls underwent complete clinical and laboratory evaluations in close proximity with their MRI studies. A higher CBF was present in the SLE group and was independently associated in statistical models with higher systolic blood pressure (SBP; p blood pressure, diastolic blood pressure, or blood levels of tissue plasminogen activator in the SLE group was significantly blunted relative to the control group. These findings are consistent with an underlying cerebral hyperperfusion in SLE induced by elevated but nonhypertensive levels of SBP. The factors underlying this relationship may be functional and/or structural (atherosclerotic, thrombotic, thromboembolic, or vasculitic) cerebrovascular disease.

  17. Relationship between retinal blood flow and arterial oxygen. (United States)

    Cheng, Richard W; Yusof, Firdaus; Tsui, Edmund; Jong, Monica; Duffin, James; Flanagan, John G; Fisher, Joseph A; Hudson, Chris


    Vascular reactivity, the response of the vessels to a vasoactive stimulus such as hypoxia and hyperoxia, can be used to assess the vascular range of adjustment in which the vessels are able to compensate for changes in PO2. Previous studies in the retina have not accurately quantified retinal vascular responses and precisely targeted multiple PaO2 stimuli at the same time as controlling the level of carbon dioxide, thus precluding them from modelling the relationship between retinal blood flow and oxygen. The present study modelled the relationship between retinal blood flow and PaO2, showing them to be a combined linear and hyperbolic function. This model demonstrates that the resting tonus of the vessels is at the mid-point and that they have great vascular range of adjustment, compensating for decreases in oxygen above a PETCO2 of 32-37 mmHg but being limited below this threshold. Retinal blood flow (RBF) increases in response to a reduction in oxygen (hypoxia) but decreases in response to increased oxygen (hyperoxia). However, the relationship between blood flow and the arterial partial pressure of oxygen has not been quantified and modelled in the retina, particularly in the vascular reserve and resting tonus of the vessels. The present study aimed to determine the limitations of the retinal vasculature by modelling the relationship between RBF and oxygen. Retinal vascular responses were measured in 13 subjects for eight different blood gas conditions, with the end-tidal partial pressure of oxygen (PETCO2) ranging from 40-500 mmHg. Retinal vascular response measurements were repeated twice; using the Canon laser blood flowmeter (Canon Inc., Tokyo, Japan) during the first visit and using Doppler spectral domain optical coherence tomography during the second visit. We determined that the relationship between RBF and PaO2 can be modelled as a combination of hyperbolic and linear functions. We concluded that RBF compensated for decreases in arterial oxygen content

  18. Evaluated Conjunctival Blood Flow Velocity in Daily Contact Lens Wearers. (United States)

    Shi, Yingying; Hu, Liang; Chen, Wan; Qu, Dongyi; Jiang, Hong; Wang, Jianhua


    This study examined conjunctival microvasculature development in long-term habitual contact lens (HCL) wearers after a night of sleep. Twenty HCL wearers (15 women and 5 men, aged 28.6±6.9 years, mean age±standard deviation) who had worn contact lenses on a daily basis for at least 3 years and 40 noncontact lens (NCL) wearers (23 women and 17 men, aged 36.5±6.6 years, mean age±standard deviation) participated in the study. A functional slitlamp biomicroscopy imaging system was used to image the temporal bulbar conjunctiva. Imaging was performed in the morning while the contact lens wearers were not wearing their lenses after a night of sleep. The conjunctival vessel diameters, blood flow velocities, and flow rates were measured. In addition, fractal analyses were performed to obtain the vessel network density (Dbox) and complexity (D0). The average blood flow velocity in HCL wearers after a night of sleep was 0.59±0.19 mm/s, which was significantly higher than that in NCL wearers (0.48±0.17 mm/s, P<0.05). The microvessel network density and complexity levels (Dbox=1.64±0.05 and D0=1.71±0.05, respectively) in the HCL wearers were significantly higher than those in NCL wearers (Dbox=1.61±0.05 and D0=1.69±0.04, both P<0.05). The blood flow velocity was positively correlated with the duration of contact lens wear (r=0.46, P<0.05) and with the daily number of lens-wearing hours (r=0.49, P<0.05) in HCL wearers. This study identified microvascular alterations in the conjunctiva in response to daily contact lens wear after a night of sleep in long-term daily contact lens wearers. The unrecovered changes may indicate that para-inflammation occurs on ocular surfaces because of contact lens wear and that overnight sleeping with no lenses may not sufficiently restore the ocular surface to an intact state.

  19. Blood pressure and blood flow variation during postural change from sitting to standing: model development and validation

    DEFF Research Database (Denmark)

    Olufsen, M.S.; Ottesen, Johnny T.; Tran, H.T.


    dynamic changes in beat-to-beat arterial blood pressure and middle cerebral artery blood flow velocity during postural change from sitting to standing. Our cardiovascular model utilizes 11 compartments to describe blood pressure, blood flow, compliance, and resistance in the heart and systemic circulation....... To include dynamics due to the pulsatile nature of blood pressure and blood flow, resistances in the large systemic arteries are modeled using nonlinear functions of pressure. A physiologically based submodel is used to describe effects of gravity on venous blood pooling during postural change. Two types...... of control mechanisms are included: 1) autonomic regulation mediated by sympathetic and parasympathetic responses, which affect heart rate, cardiac contractility, resistance, and compliance, and 2) autoregulation mediated by responses to local changes in myogenic tone, metabolic demand, and CO2 concentration...

  20. Dynamic modeling of uteroplacental blood flow in IUGR indicates vortices and elevated pressure in the intervillous space - a pilot study (United States)

    Roth, Christian J.; Haeussner, Eva; Ruebelmann, Tanja; Koch, Franz V.; Schmitz, Christoph; Frank, Hans-Georg; Wall, Wolfgang A.


    Ischemic placental disease is a concept that links intrauterine growth retardation (IUGR) and preeclampsia (PE) back to insufficient remodeling of uterine spiral arteries. The rheological consequences of insufficient remodeling of uterine spiral arteries were hypothesized to mediate the considerably later manifestation of obstetric disease. However, the micro-rheology in the intervillous space (IVS) cannot be examined clinically and rheological animal models of the human IVS do not exist. Thus, an in silico approach was implemented to provide in vivo inaccessible data. The morphology of a spiral artery and the inflow region of the IVS were three-dimensionally reconstructed to provide a morphological stage for the simulations. Advanced high-end supercomputing resources were used to provide blood flow simulations at high spatial resolution. Our simulations revealed turbulent blood flow (high-velocity jets and vortices) combined with elevated blood pressure in the IVS and increased wall shear stress at the villous surface in conjunction with insufficient spiral artery remodeling only. Post-hoc histological analysis of uterine veins showed evidence of increased trophoblast shedding in an IUGR placenta. Our data support that rheological alteration in the IVS is a relevant mechanism linking ischemic placental disease to altered structural integrity and function of the placenta.

  1. Measurement of retinal blood flow rate in diabetic rats: disparity between techniques due to redistribution of flow. (United States)

    Leskova, Wendy; Watts, Megan N; Carter, Patsy R; Eshaq, Randa S; Harris, Norman R


    Reports of altered retinal blood flow in experimental models of type I diabetes have provided contrasting results, which leads to some confusion as to whether flow is increased or decreased. The purpose of our study was to evaluate early diabetes-induced changes in retinal blood flow in diabetic rats, using two distinctly different methods. Diabetes was induced by injection of streptozotocin (STZ), and retinal blood flow rate was measured under anesthesia by a microsphere infusion technique, or by an index of flow based on the mean circulation time between arterioles and venules. Measurements in STZ rats were compared to age-matched nondiabetic controls. In addition, the retinal distribution of fluorescently-labeled red blood cells (RBCs) was viewed by confocal microscopy in excised flat mounts. Retinal blood flow rate was found to decrease by approximately 33% in the STZ rats compared to controls (P contrast, the mean circulation time through the retina was found to be almost 3× faster in the STZ rats (P < 0.01). This contradiction could be explained by flow redistribution through the superficial vessels of the diabetic retina, with this possibility supported by our observation of significantly fewer RBCs flowing through the deeper capillaries. We conclude that retinal blood flow rate is reduced significantly in the diabetic rat, with a substantial decrease of flow through the capillaries due to shunting of blood through the superficial layer, allowing rapid transit from arterioles to venules.

  2. Integration of indocyanine green videoangiography with operative microscope: augmented reality for interactive assessment of vascular structures and blood flow. (United States)

    Martirosyan, Nikolay L; Skoch, Jesse; Watson, Jeffrey R; Lemole, G Michael; Romanowski, Marek; Anton, Rein


    Preservation of adequate blood flow and exclusion of flow from lesions are key concepts of vascular neurosurgery. Indocyanine green (ICG) fluorescence videoangiography is now widely used for the intraoperative assessment of vessel patency. Here, we present a proof-of-concept investigation of fluorescence angiography with augmented microscopy enhancement: real-time overlay of fluorescence videoangiography within the white light field of view of conventional operative microscopy. The femoral artery was exposed in 7 anesthetized rats. The dissection microscope was augmented to integrate real-time electronically processed near-infrared filtered images with conventional white light images seen through the standard oculars. This was accomplished by using an integrated organic light-emitting diode display to yield superimposition of white light and processed near-infrared images. ICG solution was injected into the jugular vein, and fluorescent femoral artery flow was observed. Fluorescence angiography with augmented microscopy enhancement was able to detect ICG fluorescence in a small artery of interest. Fluorescence appeared as a bright-green signal in the ocular overlaid with the anatomic image and limited to the anatomic borders of the femoral artery and its branches. Surrounding anatomic structures were clearly visualized. Observation of ICG within the vessel lumens permitted visualization of the blood flow. Recorded video loops could be reviewed in an offline mode for more detailed assessment of the vasculature. The overlay of fluorescence videoangiography within the field of view of the white light operative microscope allows real-time assessment of the blood flow within vessels during simultaneous surgical manipulation. This technique could improve intraoperative decision making during complex neurovascular procedures.

  3. [Cockett's syndrome, May-Thurner syndrome, or iliac vein compression syndrome]. (United States)

    Gil Martín, A R; Carreras Aja, M; Arrieta Ardieta, I; Labayen Azparren, I


    Iliac vein compression syndrome (also known as May-Thurner syndrome or Cockett's syndrome) is a rare clinical entity in which the left common iliac vein is compressed when it passes between the right common iliac artery and the spine. The sustained compression and trauma caused by the pulsatile force of the artery on the vein damage the intima and lead to the formation of membranes or bands in the vascular lumen that hinder or obstruct the flow of blood in the vein, favoring thrombus formation. The current treatment strategy of choice is endovascular vein patch angioplasty and stenting with the aim of improving the caliber of the lumen and enabling normal venous drainage. We present two cases of May-Thurner syndrome and review the clinical and CT findings. Copyright © 2011 SERAM. Published by Elsevier Espana. All rights reserved.

  4. Regional heterogeneity of endothelial cells in the porcine vortex vein system. (United States)

    Tan, Priscilla Ern Zhi; Yu, Paula K; Cringle, Stephen J; Morgan, William H; Yu, Dao-Yi


    The aim of this study was to investigate whether region-dependent endothelial heterogeneity is present within the porcine vortex vein system. The superior temporal vortex vein in young adult pig eyes were dissected out and cannulated. The intact vortex vein system down to the choroidal veins was then perfused with labels for f-actin and nucleic acid. The endothelial cells within the choroidal veins, pre-ampulla, anterior portion of the ampulla, mid-ampulla, posterior portion of the ampulla, post-ampulla, intra-scleral canal and the extra-ocular vortex vein regions were studied in detail using a confocal microscopy technique. The endothelial cell and nuclei length, width, area and perimeter were measured and compared between the different regions. Significant regional differences in the endothelial cell and nuclei length, width, area and perimeter were observed throughout the porcine vortex vein system. Most notably, very narrow and elongated endothelia were found in the post-ampulla region. A lack of smooth muscle cells was noted in the ampulla region compared to other regions. Heterogeneity in endothelial cell morphology is present throughout the porcine vortex vein system and there is a lack of smooth muscle cells in the ampulla region. This likely reflects the highly varied haemodynamic conditions and potential blood flow control mechanisms in different regions of the vortex vein system. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. High flow rates during modified ultrafiltration decrease cerebral blood flow velocity and venous oxygen saturation in infants. (United States)

    Rodriguez, Rosendo A; Ruel, Marc; Broecker, Lothar; Cornel, Garry


    The intracranial hemodynamic effects of modified ultrafiltration in children are unknown. We investigated the effects of different blood flow rates during modified ultrafiltration on the cerebral hemodynamics of children with weights above and below 10 kg. Thirty-one children (weights: 10 kg, n = 10) undergoing cardiopulmonary bypass were studied. Middle-cerebral artery blood flow velocities and cerebral mixed venous oxygen saturations were measured before, five minutes from the beginning, and at the end of ultrafiltration. Patients were classified according to their blood flow rates during ultrafiltration in three groups: high (> or = 20 mL/kg/min), moderate (10-19 mL/kg/min), and low flow rates (flow rates of ultrafiltration and the decline in mean cerebral blood flow velocity (r = - 0.48; p = 0.005) and cerebral oxygen saturation (r = - 0.49; p = 0.005) or hematocrit increase (r = 0.59; p = 0.001). Infants exposed to high flow rates had greater reduction of cerebral blood flow velocity and regional mixed venous saturation and higher hematocrit at the end of ultrafiltration compared with those subjected to moderate and low flow rates (p flow rates through the ultrafilter during modified ultrafiltration transiently decrease the cerebral circulation in young infants compared with lower blood flow rates. These effects may be related to an increased diastolic runoff from the aorta into the ultrafiltration circuit that leads to a "stealing" effect from the intracranial circulation, which may be important in infants with dysfunctional cerebral autoregulation.

  6. Reflectometric mapping of microregional blood flow and blood volume in the brain cortex. (United States)

    Eke, A


    A reflectometric indicator-dilution method has been developed for mapping the parenchymal minute volume flow and blood content over tiny superficial areas of the brain cortex at 625 or 2500 locations, respectively. About 0.4 ml dextran-saline solution was used as nondiffusible indicator and injected into the feline cerebral circulation for each measurement. The subsequent cerebrocortical transit of the hemodiluted bolus was detected as a temporary change in the tissue optical density [OD(t)] and interpreted as indicator dilution, C(t). This gave the data necessary to calculate the microregional blood volume (mrCBV), mean transit time of the bolus (mrMTT), and the microregional blood flow (mrCBF = mrCBV/mrMTT). A two-dimensional record of the OD(t) function was made on Kodak SO 115 film by 16-mm cinematography, as a reflectometric tool, over an exposed area of the brain cortex during the bolus perfusion. Later, the microregional OD(t) functions were retrieved for analysis in a square array from the developed film by computer-controlled, frame-by-frame scanning densitometry. Maps of mrCBF, mrCBV, and mrMTT were presented as square arrays of gray-scaled pixels. The maximal spatial and temporal resolution of the method was 0.015 mm2 (mrCBF), 0.004 mm2 (mrCBV), 6 maps/min (mrCBF), and 600 maps/min (mrCBV).

  7. Measuring Cerebral Blood Flow in Moyamoya Angiopathy by Quantitative Magnetic Resonance Angiography Noninvasive Optimal Vessel Analysis. (United States)

    Khan, Nadia; Lober, Robert M; Ostergren, Lauren; Petralia, Jacob; Bell-Stephens, Teresa; Navarro, Ramon; Feroze, Abdullah; Steinberg, Gary K


    Moyamoya disease causes progressive occlusion of the supraclinoidal internal carotid artery, and middle, anterior, and less frequently the posterior cerebral arteries, carrying the risk of stroke. Blood flow is often partially reconstituted by compensatory moyamoya collaterals and sometimes the posterior circulation. Cerebral revascularization can further augment blood flow. These changes to blood flow within the cerebral vessels, however, are not well characterized. To evaluate blood flow changes resulting from the disease process and revascularization surgery using quantitative magnetic resonance angiography with noninvasive optimal vessel analysis (NOVA). We retrospectively analyzed 190 preoperative and postoperative imaging scans in 66 moyamoya patients after revascularization surgery. Images were analyzed for blood flow using NOVA and compared with preoperative angiographic staging and postoperative blood flow. Blood flow rates within superficial temporal artery grafts were compared based on angiographic evidence of patency. Diseased vessels had lower blood flow, correlating with angiographic staging. Flow in posterior cererbal and basilar arteries increased with disease severity, particularly when both the anterior and middle cerebral arteries were occluded. Basilar artery flow and ipsilateral internal carotid artery flow decreased after surgery. Flow rates were different between angiographically robust and poor direct bypass grafts, as well as between robust and patent grafts. Preoperative changes in cerebral vessel flow as measured by NOVA correlated with angiographic disease progression. NOVA demonstrated that preoperative augmentation of the posterior circulation decreased after surgery. This report is the first to quantify the shift in collateral supply from the posterior circulation to the bypass graft.

  8. Varicose vein - noninvasive treatment (United States)

    Sclerotherapy; Laser therapy - varicose veins; Radiofrequency vein ablation; Endovenous thermal ablation; Ambulatory phlebectomy; Transilluminated power phlebotomy; Endovenous laser ablation; Varicose vein ...

  9. Non-invasive determination of instantaneous brachial blood flow using the oscillometric method. (United States)

    Liu, Shing-Hong; Wang, Jia-Jung; Cheng, Da-Chuan


    The oscillometric method has been widely used to measure arterial systolic and diastolic blood pressures, but its potential for arterial blood flow measurements still remains to be explored. The aim of this study was to non-invasively determine arterial blood flow using an oscillometric blood flow measurement system. The system consists of a pneumatic elastic cuff, an air-pumping motor, a releaser valve, a pressure transducer, and an airflow meter. To build a non-linear cuff model, we measured airflow pumped into the pneumatic cuff and cuff pressure using an airflow meter and pressure transducer during the inflation period, respectively. During the deflation period, only the pressure transducer was used to record cuff pressure. Based on the cuff model, the oscillometric blood flow waveform was obtained by integrating the oscillometric pressure waveform. We compared arterial blood flow derived from the maximum amplitude of the oscillometric blood flow waveform with Doppler-measured blood flow calculated with the diameters and blood velocities of the brachial arteries in 32 subjects who underwent diagnostic evaluations for peripheral arterial embolism. A linear correlation coefficient of r = 0.716 was found between the oscillometry- and Doppler-based blood flow measurements in the 32 subjects. These results suggest that blood flow passing through the brachial artery can be quantified non-invasively using the oscillometric approach after appropriate calibration.

  10. Measurement of hemodynamic changes with the axial flow blood pump installed in descending aorta. (United States)

    Okamoto, Eiji; Yano, Tetsuya; Miura, Hidekazu; Shiraishi, Yasuyuki; Yambe, Tomoyuki; Mitamura, Yoshinori


    We have developed various axial flow blood pumps to realize the concept of the Valvo pump, and we have studied hemodynamic changes under cardiac assistance using an axial flow blood pump in series with the natural heart. In this study, we measured hemodynamic changes of not only systemic circulation but also cerebral circulation and coronary circulation under cardiac support using our latest axial flow blood pump placed in the descending aorta in an acute animal experiment. The axial flow blood pump was installed at the thoracic descending aorta through a left thoracotomy of a goat (43.8 kg, female). When the pump was on, the aortic pressure and aortic flow downstream of the pump increased with preservation of pulsatilities. The pressure drop upstream of the pump caused reduction of afterload pressure, and it may lead to reduction of left ventricular wall stress. However, cerebral blood flow and coronary blood flow were decreased when the pump was on. The axial flow blood pump enables more effective blood perfusion into systemic circulation, but it has the potential risk of blood perfusion disturbance into cerebral circulation and coronary circulation. The results indicate that the position before the coronary ostia might be suitable for implantation of the axial flow blood pump in series with the natural heart to avoid blood perfusion disturbances.

  11. Optical measurement of blood flow in exercising skeletal muscle: a pilot study (United States)

    Wang, Detian; Baker, Wesley B.; Parthasarathy, Ashwin B.; Zhu, Liguo; Li, Zeren; Yodh, Arjun G.


    Blood flow monitoring during rhythm exercising is very important for sports medicine and muscle dieases. Diffuse correlation spectroscopy(DCS) is a relative new invasive way to monitor blood flow but suffering from muscle fiber motion. In this study we focus on how to remove exercise driven artifacts and obtain accurate estimates of the increase in blood flow from exercise. Using a novel fast software correlator, we measured blood flow in forearm flexor muscles of N=2 healthy adults during handgrip exercise, at a sampling rate of 20 Hz. Combining the blood flow and acceleration data, we resolved the motion artifact in the DCS signal induced by muscle fiber motion, and isolated the blood flow component of the signal from the motion artifact. The results show that muscle fiber motion strongly affects the DCS signal, and if not accounted for, will result in an overestimate of blood flow more than 1000%. Our measurements indicate rapid dilation of arterioles following exercise onset, which enabled blood flow to increase to a plateau of 200% in 10s. The blood flow also rapidly recovered to baseline following exercise in 10s. Finally, preliminary results on the dependence of blood flow from exercise intensity changes will be discussed.

  12. Effect of couple stresses on hydromagnetic flow of blood through a ...

    African Journals Online (AJOL)

    The function of the coronary network is to supply blood to the heart; however, in cases of Coronary Artery Disease, the geometry has great influence on the nature of the blood flow and the overall performance of the heart. In this paper, the unsteady non-Newtonian flow of blood under couple stresses and a uniform external ...

  13. Increased chemiluminescence and ulcer development in the low blood flow state of the gastric tube for esophageal replacement. (United States)

    Aiko, S; Ando, N; Shinozawa, Y; Ozawa, S; Kitajima, M; Kurose, I; Tsuchiya, M


    Peptic ulcers in the gastric tube for esophageal replacement develop in spite of reduction of acid secretion after truncal vagotomy and often result in serious conditions such as bleeding and perforation. Thirteen cases of gastric tube ulcers were detected endoscopically from 1985 to 1990 in our hospital. Most of these ulcers developed within 20 cm of the anastomosis (esophagogastrostomy), which was an especially hypoxic and ischemic area. Ischemic change due to decreased blood supply is suggested as a causative factor in ulcer development. Recent studies indicate that chemiluminescence (ChL) activity may increase even in the low-flow hypoxic condition. Therefore, we investigated the ChL of regional blood in the hypoxic gastric tube in dogs. The ChL activity of the blood sample collected from the ischemic region in the gastric tube significantly increased after construction of the gastric tube, compared with systemic blood from the femoral vein, and the number of leukocytes decreased in the ischemic region. We believe that oxygen radicals derived from neutrophils adhering to the vascular endothelium may play an important role in the damage to endothelial cells of the gastric tube and suggest the possibility of their causative effects in the process of ulcer formations.

  14. Two and Three Dimensional Blood Flow Simulations in Different Types of Blood Vessels

    Directory of Open Access Journals (Sweden)

    Balazs ALBERT


    Full Text Available In this paper we present a synthesis of our results obtained on blood flow simulation in different types of blood vessels. We present first some remarks on the wall shear stress (WSS in the case of a human abdominal aortic aneurysm (AAA, and then we concentrate on the mechanical conditions which would lead to the “rupture” of the vascular vessel with aneurysm and implicitly to a possible stroke. We also make some investigations on the Fahraeus-Lindqvist effect in arterioles. Considering an axial-symmetric reservoir full of blood and which is linked to an arteriole (with the same particular geometry, we have pointed out the concentration of the red blood cells in this arteriole towards the core of the vessel. To improve our work we have considered a real three-dimensional geometry, which is a serious jump versus our previous results, where only the axial-symmetric geometries were considered. In this respect we have reconsidered the case of a carotid artery stenosis with and without a stent.

  15. Intensive blood pressure lowering increases cerebral blood flow in older subjects with hypertension. (United States)

    Tryambake, Dinesh; He, Jiabao; Firbank, Michael J; O'Brien, John T; Blamire, Andrew M; Ford, Gary A


    Hypertension is associated with reduced cerebral blood flow (CBF). Intensive (blood pressure (BP) lowering in older people might give greater reduction in cardiovascular risk, but there are concerns that this might produce hypoperfusion which may precipitate falls and possibly stroke. We determined the effect of intensive compared with usual BP lowering on CBF in hypertensive older subjects. Individuals aged >70 years with a history of systolic hypertension on 1 or no BP lowering drugs were recruited from primary care (n=37; age, 75±4 years; systolic BP, >150 mm Hg) and randomized to receive intensive (target BP, hypertension increases CBF, compared with BP lowering to usual target. These findings suggest hypertension in older people shifts the autoregulatory CBF curve rightward and downward and is reversible with BP lowering.

  16. Intensive blood pressure control affects cerebral blood flow in type 2 diabetes mellitus patients

    DEFF Research Database (Denmark)

    Kim, Yu-Sok; Davis, Shyrin C A T; Truijen, Jasper


    Type 2 diabetes mellitus is associated with microvascular complications, hypertension, and impaired dynamic cerebral autoregulation. Intensive blood pressure (BP) control in hypertensive type 2 diabetic patients reduces their risk of stroke but may affect cerebral perfusion. Systemic hemodynamic...... variables and transcranial Doppler-determined cerebral blood flow velocity (CBFV), cerebral CO2 responsiveness, and cognitive function were determined after 3 and 6 months of intensive BP control in 17 type 2 diabetic patients with microvascular complications (T2DM+), in 18 diabetic patients without (T2DM...... patients with microvascular complications, indicating that maintenance of cerebral perfusion during BP treatment depends on the progression of microvascular disease. We suggest that BP treatment should be individualized, aiming at a balance between BP reduction and maintenance of CBFV....

  17. A simple model of cerebral blood flow dependence on arterial blood pressure

    CERN Document Server

    Gersten, Alexander


    It is shown that the dependence of the cerebral blood flow (CBF) on mean arterial blood pressure (MABP) can be described with a simple model having the following assumptions. Below certain MABP (denoted as MABP1) there are no autoregulatory or feedback mechanisms influencing CBF. Between MABP1 and MABP2 (MABP at which breakthrough accurs) there is a linear (on MABP) dependent feedback with a sloap depending very much on the individual considered. The classical autoregulation model with a plateau in between MABP1 and MABP2 is a particular case of this model. The model describes well the experiments performed on dogs (Harper 1966), for which the individual feedback sloap parameter varied to great extent, indicating the importance of mesurments on individuals against averaged mesurments (or measurments on diffent individuals) which superficially support the classical autoregulation. New effect of decreased CBF, while increasing MABP, was observed.

  18. An accurate, flexible and small optical fiber sensor: a novel technological breakthrough for real-time analysis of dynamic blood flow data in vivo. (United States)

    Yuan, Qiao-ying; Zhang, Ling; Xiao, Dan; Zhao, Kun; Lin, Chun; Si, Liang-yi


    Because of the limitations of existing methods and techniques for directly obtaining real-time blood data, no accurate microflow in vivo real-time analysis method exists. To establish a novel technical platform for real-time in vivo detection and to analyze average blood pressure and other blood flow parameters, a small, accurate, flexible, and nontoxic Fabry-Perot fiber sensor was designed. The carotid sheath was implanted through intubation of the rabbit carotid artery (n = 8), and the blood pressure and other detection data were determined directly through the veins. The fiber detection results were compared with test results obtained using color Doppler ultrasound and a physiological pressure sensor recorder. Pairwise comparisons among the blood pressure results obtained using the three methods indicated that real-time blood pressure information obtained through the fiber sensor technique exhibited better correlation than the data obtained with the other techniques. The highest correlation (correlation coefficient of 0.86) was obtained between the fiber sensor and pressure sensor. The blood pressure values were positively related to the total cholesterol level, low-density lipoprotein level, number of red blood cells, and hemoglobin level, with correlation coefficients of 0.033, 0.129, 0.358, and 0.373, respectively. The blood pressure values had no obvious relationship with the number of white blood cells and high-density lipoprotein and had a negative relationship with triglyceride levels, with a correlation coefficient of -0.031. The average ambulatory blood pressure measured by the fiber sensor exhibited a negative correlation with the quantity of blood platelets (correlation coefficient of -0.839, Preal time; the sensor can also determine the content and status of the blood flow to some extent. Therefore, the fiber sensor can obtain partially real-time vascular rheology information and may thus enable the early diagnosis of blood rheology disorders and

  19. Blood-brain barrier and cerebral blood flow: Age differences in hemorrhagic stroke

    Directory of Open Access Journals (Sweden)

    Semyachkina-Glushkovskaya Oxana


    Full Text Available Neonatal stroke is similar to the stroke that occurs in adults and produces a significant morbidity and long-term neurologic and cognitive deficits. There are important differences in the factors, clinical events and outcomes associated with the stroke in infants and adults. However, mechanisms underlying age differences in the stroke development remain largely unknown. Therefore, treatment guidelines for neonatal stroke must extrapolate from the adult data that is often not suitable for children. The new information about differences between neonatal and adult stroke is essential for identification of significant areas for future treatment and effective prevention of neonatal stroke. Here, we studied the development of stress-induced hemorrhagic stroke and possible mechanisms underlying these processes in newborn and adult rats. Using histological methods and magnetic resonance imaging, we found age differences in the type of intracranial hemorrhages. Newborn rats demonstrated small superficial bleedings in the cortex while adult rats had more severe deep bleedings in the cerebellum. Using Doppler optical coherent tomography, we found higher stress-reactivity of the sagittal sinus to deleterious effects of stress in newborn vs. adult rats suggesting that the cerebral veins are more vulnerable to negative stress factors in neonatal vs. adult brain in rats. However, adult but not newborn rats demonstrated the stroke-induced breakdown of blood brain barrier (BBB permeability. The one of possible mechanisms underlying the higher resistance to stress-related stroke injures of cerebral vessels in newborn rats compared with adult animals is the greater expression of two main tight junction proteins of BBB (occludin and claudin-5 in neonatal vs. mature brain in rats.

  20. Upper limit of cerebral blood flow autoregulation in experimental renovascular hypertension in the baboon

    DEFF Research Database (Denmark)

    Strandgaard, S; Jones, J V; MacKenzie, E T


    The effect of arterial hypertension on cerebral blood flow was studied by the intracarotid 133Xe clearance method in baboons. The arterial blood pressure was raised in gradual steps with angiotensin. Baboons with renal hypertension of 8-12 weeks duration were studied along with normotensive baboons....... In initially normotensive baboons, cerebral blood flow remained constant until the mean arterial blood pressure had risen to the range of 140 to 154 mm Hg; thereafter cerebral blood flow increased with each rise in mean arterial blood pressure. In the chronically hypertensive baboons, cerebral blood flow...... remained constant until the mean arterial blood pressure had been elevated to the range of 155 to 169 mm Hg. Thus, in chronic hypertension it appears that there are adaptive changes in the cerebral circulation which may help to protect the brain from further increases in arterial blood pressure....

  1. Quantitative assessment of limb blood flow using Tc-99m labeled red blood cells. Radionuclide venous occlusion plethysmography (RAVOP)

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Kazuo; Shougase, Takashi; Kawamura, Naoyuki; Tsukamoto, Eriko; Nakada, Kunihiro; Sakuma, Makoto; Furudate, Masayori


    A quantitative assessment of limb blood flow using a non-diffusible radioindicator, Tc-99m labeled red blood cells, was reported. This was an application of venous occlusion plethysmography using radionuclide which was originally proposed by M. Fukuoka et al. The peripheral blood flow (mean +- s.e.) of 30 legs in a normal control group was 1.87 +- 0.08 ml/100 ml/min. In heart diseases (46 legs), it was 1.49 +- 0.13 ml/100 ml/min. The limb blood flow between a control group and heart diseases was statistically significant (p < 0.01) in the t-test. The peripheral blood flow at rest between diseased legs and normal legs in occlusive arterial disorders was also statistically significant (p < 0.01) in a paired t-test. RAVOP was done after the completion of objective studies such as radionuclide angiography or ventriculography. Technique and calculation of a blood flow were very easy and simple. RAVOP study which was originally proposed by Fukuoka et al. was reappraised to be hopeful for quantitative measurement of limb blood flow as a non-invasive technique using Tc-99m labeled red blood cells.

  2. Correlation of volumetric flow rate and skin blood flow with cold intolerance in digital replantation. (United States)

    Zhao, Gang; Mi, Jingyi; Rui, Yongjun; Pan, Xiaoyun; Yao, Qun; Qiu, Yang


    Cold intolerance is a common complication of digital replantation. The exact etiology is unclear, but it is considered to be multifactorial, including nonsurgical characteristics, vascular, and neurologic conditions. Blood flow may play a significant role in cold intolerance. This study was designed to evaluate the correlation of digital blood flow, including volumetric flow rate (VFR) and skin blood flow (SkBF), with cold intolerance in replanted fingers.A retrospective study was conducted among patients who underwent digital replantation between 2010 and 2013. Patients were selected into study cohort based on the inclusion criteria. Surgical data was collected on each patient, including age, sex, injury mechanism, amputation level, ischemia time, number of arteries repaired, and whether or not vascular crisis occurred. Patients were included as study cohort with both nerves repaired and without chronic disease. Cold intolerance was defined as a Cold Intolerance Symptom Severity (CISS) score over 30. The arterial flow velocity and caliber were measured by Color Doppler Ultrasound and the digital VFR was calculated. The SkBF was measured by Laser Speckle Imager. Both VFR and SkBF were calculated as a percentage of the contralateral fingers. Comparative study of surgical data and blood flow was performed between the patient with and without cold intolerance. Correlation between VFR and SkBF was also analyzed.A total of 93 patients met inclusion criteria for the study. Approximately, 42 patients were identified as having cold intolerance. Fingers that survived vascular crisis had a higher incidence of cold intolerance with a lower VFR and SkBF. The VFR was higher in 2-artery replantation, but the SkBF and incidence of cold intolerance did not differ significantly. No differences were found in age, sex, injury mechanism, amputation level, or ischemia time. Furthermore, no correlation was found between VFR and SkBF.Cold intolerance of digital replantation is associated

  3. Middle cerebral artery blood velocity and cerebral blood flow and O2 uptake during dynamic exercise

    DEFF Research Database (Denmark)

    Madsen, P L; Sperling, B K; Warming, T


    Results obtained by the 133Xe clearance method with external detectors and by transcranial Doppler sonography (TCD) suggest that dynamic exercise causes an increase of global average cerebral blood flow (CBF). These data are contradicted by earlier data obtained during less-well-defined conditions....... To investigate this controversy, we applied the Kety-Schmidt technique to measure the global average levels of CBF and cerebral metabolic rate of oxygen (CMRO2) during rest and dynamic exercise. Simultaneously with the determination of CBF and CMRO2, we used TCD to determine mean maximal flow velocity...... in the middle cerebral artery (MCA Vmean). For values of CBF and MCA Vmean a correction for an observed small drop in arterial PCO2 was carried out. Baseline values for global CBF and CMRO2 were 50.7 and 3.63 ml.100 g-1.min-1, respectively. The same values were found during dynamic exercise, whereas a 22% (P

  4. Effects of respiratory muscle work on respiratory and locomotor blood flow during exercise. (United States)

    Dominelli, Paolo B; Archiza, Bruno; Ramsook, Andrew H; Mitchell, Reid A; Peters, Carli M; Molgat-Seon, Yannick; Henderson, William R; Koehle, Michael S; Boushel, Robert; Sheel, A William


    What is the central question of this study? Does manipulation of the work of breathing during high-intensity exercise alter respiratory and locomotor muscle blood flow? What is the main finding and its importance? We found that when the work of breathing was reduced during exercise, respiratory muscle blood flow decreased, while locomotor muscle blood flow increased. Conversely, when the work of breathing was increased, respiratory muscle blood flow increased, while locomotor muscle blood flow decreased. Our findings support the theory of a competitive relationship between locomotor and respiratory muscles during intense exercise. Manipulation of the work of breathing (WOB) during near-maximal exercise influences leg blood flow, but the effects on respiratory muscle blood flow are equivocal. We sought to assess leg and respiratory muscle blood flow simultaneously during intense exercise while manipulating WOB. Our hypotheses were as follows: (i) increasing the WOB would increase respiratory muscle blood flow and decrease leg blood flow; and (ii) decreasing the WOB would decrease respiratory muscle blood flow and increase leg blood flow. Eight healthy subjects (n = 5 men, n = 3 women) performed a maximal cycle test (day 1) and a series of constant-load exercise trials at 90% of peak work rate (day 2). On day 2, WOB was assessed with oesophageal balloon catheters and was increased (via resistors), decreased (via proportional assist ventilation) or unchanged (control) during the trials. Blood flow was assessed using near-infrared spectroscopy optodes placed over quadriceps and the sternocleidomastoid muscles, coupled with a venous Indocyanine Green dye injection. Changes in WOB were significantly and positively related to changes in respiratory muscle blood flow (r = 0.73), whereby increasing the WOB increased blood flow. Conversely, changes in WOB were significantly and inversely related to changes in locomotor blood flow (r = 0.57), whereby decreasing the

  5. Iodoamphetamine as a new tracer for local cerebral blood flow in the rat

    DEFF Research Database (Denmark)

    Rapin, J R; Le Poncin-Lafitte, M; Duterte, D


    blood flow and a more real estimation of hippocampal flow. It is concluded from the brain uptake of the derivatives of both amphetamines during the first minutes following their injection that these tracers can be used as a chemical microembolus for the measurement of local cerebral blood flow....

  6. Biology and Mechanics of Blood Flows Part I: Biology

    CERN Document Server

    Thiriet, Marc


    Biology and Mechanics of Blood Flows presents the basic knowledge and state-of-the-art techniques necessary to carry out investigations of the cardiovascular system using modeling and simulation. Part I of this two-volume sequence, Biology, addresses the nanoscopic and microscopic scales. The nanoscale corresponds to the scale of biochemical reaction cascades involved in cell adaptation to mechanical stresses among other stimuli. The microscale is the scale of stress-induced tissue remodeling associated with acute or chronic loadings. The cardiovascular system, like any physiological system, has a complicated three-dimensional structure and composition. Its time dependent behavior is regulated, and this complex system has many components. In this authoritative work, the author provides a survey of relevant cell components and processes, with detailed coverage of the electrical and mechanical behaviors of vascular cells, tissues, and organs. Because the behaviors of vascular cells and tissues are tightly coupl...

  7. Bifurcation study of blood flow control in the kidney (United States)

    Ford Versypt, Ashlee N.; Makrides, Elizabeth; Arciero, Julia C.; Ellwein, Laura; Layton, Anita T.


    Renal blood flow is maintained within a narrow window by a set of intrinsic autoregulatory mechanisms. Here, a mathematical model of renal hemodynamics control in the rat kidney is used to understand the interactions between two major renal autoregulatory mechanisms: the myogenic response and tubuloglomerular feedback. A bifurcation analysis of the model equations is performed to assess the effects of the delay and sensitivity of the feedback system and the time constants governing the response of vessel diameter and smooth muscle tone. The results of the bifurcation analysis are verified using numerical simulations of the full nonlinear model. Both the analytical and numerical results predict the generation of limit cycle oscillations under certain physiologically relevant conditions, as observed in vivo. PMID:25747903

  8. History of International Society for Cerebral Blood Flow and Metabolism

    DEFF Research Database (Denmark)

    Paulson, Olaf B; Kanno, Iwao; Reivich, Martin


    Interest in the brain's circulation dates back more than a century and has been steadily growing. Quantitative methods for measurements of cerebral blood flow (CBF) and energy metabolism became available in the middle of the 20th century and gave a new boost to the research. Scientific meetings...... since then been a major success. The development of new brain imaging methods has had a major impact. Regulation of CBF and ischemia has been the main topics at the meetings. A new field of brain mapping research emerged and has now its own society and meetings. Brain emission tomography research has...... grown within the society and is now an integrated part. The ISCBFM is a sound society, and support of young scientists is among its goals. Several awards have been established. Other activities including summer schools, courses, satellite meetings, and Gordon conferences have contributed to the success...

  9. Cerebral blood flow response to propranolol in streptozotocin diabetic rats

    DEFF Research Database (Denmark)

    Lass, Preben; Knudsen, G M


    The influence of propranolol on cerebral blood flow (CBF) was tested in streptozotocin diabetic rats and in control animals. Resting CBF values were 40% lower in the diabetic rats compared with controls. Intravenous injection of propranolol (2 mg kg-1) decreased CBF significantly in the control...... group; the CBF decreased for 15 min after propranolol injection and returned to baseline values after 90 min. In the diabetic rats, the CBF declined steadily but this decrease did not reach significance, even after 90 min. Impaired beta-adrenergic mechanisms may be an important factor in the CBF...... alterations which occur in diabetes mellitus. Further, it is suggested that an impaired CBF response may play a role in CNS lesions in diabetic patients treated with beta antagonists....

  10. Repeated blood flow restriction induces muscle fiber hypertrophy. (United States)

    Sudo, Mizuki; Ando, Soichi; Kano, Yutaka


    We recently developed an animal model to investigate the effects of eccentric contraction (ECC) and blood flow restriction (BFR) on muscle tissue at the cellular level. This study clarified the effects of repeated BFR, ECC, and BFR combined with ECC (BFR+ECC) on muscle fiber hypertrophy. Male Wistar rats were assigned to 3 groups: BFR, ECC, and BFR+ECC. The contralateral leg in the BFR group served as a control (CONT). Muscle fiber cross-sectional area (CSA) of the tibialis anterior was determined after the respective treatments for 6 weeks. CSA was greater in the BFR+ECC group than in the CONT (P hypertrophy at the cellular level. Muscle Nerve 55: 274-276, 2017. © 2016 Wiley Periodicals, Inc.

  11. Cerebral blood flow and oxygen metabolism in the Rett syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Yoshikawa, Hideto; Fueki, Noboru; Suzuki, Hisaharu; Sakuragawa, Norio; Iio, Masaaki (National Central Hospital for Mental, Nervous and Muscular Disorders, Tokyo (Japan))


    Positron emission tomography (PET) was performed on six patients with the Rett syndrome and the results were compared with the concurrent clinical status of the patients. The cerebral metabolic rate of oxygen (CMRO{sub 2}) was low in five patients, and oxygen extraction fraction (OEF) was low in four patients; both had a tendency to decline with advancing age. Although the cause is unknown, it is suggested that impaired oxidative metabolism exists in the Rett syndrome. An analysis of the distribution among brain regions showed that the ratios of values for the frontal cortex to those for the temporal cortex for both the cerebral blood flow (CBF) and CMRO{sub 2} were lower than those for the controls, which may indicate the loss of of hyperfrontality in the Rett syndrome. Distribution of brain metabolism may be immature in the Rett syndrome. (author).

  12. Brain energy metabolism and blood flow differences in healthy aging

    DEFF Research Database (Denmark)

    Aanerud, Joel; Borghammer, Per; Chakravarty, M Mallar


    Cerebral metabolic rate of oxygen consumption (CMRO(2)), cerebral blood flow (CBF), and oxygen extraction fraction (OEF) are important indices of healthy aging of the brain. Although a frequent topic of study, changes of CBF and CMRO(2) during normal aging are still controversial, as some authors...... find decreases of both CBF and CMRO(2) but increased OEF, while others find no change, and yet other find divergent changes. In this reanalysis of previously published results from positron emission tomography of healthy volunteers, we determined CMRO(2) and CBF in 66 healthy volunteers aged 21 to 81......, and in the temporal cortex. Because of the inverse relation between OEF and capillary oxygen tension, increased OEF can compromise oxygen delivery to neurons, with possible perturbation of energy turnover. The results establish a possible mechanism of progression from healthy to unhealthy brain aging, as the regions...

  13. Cerebral Blood Flow Responses to Aquatic Treadmill Exercise. (United States)

    Parfitt, Rhodri; Hensman, Marianne Y; Lucas, Samuel J E


    Aquatic treadmills are used as a rehabilitation method for conditions such as spinal cord injury, osteoarthritis, and stroke, and can facilitate an earlier return to exercise training for athletes. However, their effect on cerebral blood flow (CBF) responses has not been examined. We tested the hypothesis that aquatic treadmill exercise would augment CBF and lower HR compared with land-based treadmill exercise. Eleven participants completed incremental exercise (crossover design) starting from walking pace (4 km·h, immersed to iliac crest [aquatic], 6 km·h [land]) and increasing 1 km·h every 2 min up to 10 km·h for aquatic (maximum belt speed) or 12 km·h for land. After this, participants completed two 2-min bouts of exercise immersed to midthigh and midchest at constant submaximal speed (aquatic), or were ramped to exhaustion (land; increased gradient 2° every min). Middle cerebral artery blood flow velocity (MCAv) and HR were measured throughout, and the initial 10 min of each protocol and responses at each immersion level were compared. Compared with land-based treadmill, MCAvmean increased more from baseline for aquatic exercise (21% vs 12%, P aquatic walking compared with land-based moderate intensity running (~10 cm·s, P = 0.56). Greater water immersion lowered HR (139 vs 178 bpm for midchest vs midthigh), whereas MCAvmean remained constant (P = 0.37). Findings illustrate the potential for aquatic treadmill exercise to enhance exercise-induced elevations in CBF and thus optimize shear stress-mediated adaptation of the cerebrovasculature.

  14. Quantification of hepatic blood flow using a high-resolution phase-contrast MRI sequence with compressed sensing acceleration. (United States)

    Dyvorne, Hadrien A; Knight-Greenfield, Ashley; Besa, Cecilia; Cooper, Nancy; Garcia-Flores, Julio; Schiano, Thomas D; Markl, Michael; Taouli, Bachir


    OBJECTIVE. The objective of our study was to evaluate the performance of a high-spatial-resolution 2D phase-contrast (PC) MRI technique accelerated with compressed sensing for portal vein (PV) and hepatic artery (HA) flow quantification in comparison with a standard PC MRI sequence. SUBJECTS AND METHODS. In this prospective study, two PC MRI sequences were compared, one with parallel imaging acceleration and low spatial resolution (generalized autocalibrating partial parallel acquisition [GRAPPA]) and one with compressed sensing acceleration and high spatial resolution (sparse). Seventy-six patients were assessed, including 37 patients with cirrhosis. Two observers evaluated PC image quality. Quantitative analyses yielded a mean velocity, flow, and vessel area for the PV and HA and an arterial fraction. The PC techniques were compared using the paired Wilcoxon test and Bland-Altman statistics. The sensitivity of the flow parameters to the severity of cirrhosis was also assessed. RESULTS. Vessel delineation was significantly improved using the PC sparse sequence (p spatial-resolution highly accelerated compressed sensing technique (PC sparse) allows total hepatic blood flow measurements obtained in 1 breath-hold, provides improved delineation of the hepatic vessels compared with a standard PC MRI sequence (GRAPPA), and can potentially be used for the noninvasive assessment of liver cirrhosis.


    Directory of Open Access Journals (Sweden)

    Alan Kacin


    Full Text Available Blood flow restricted resistance (BFRR training with pneumatic tourniquet has been suggested as an alternative for conventional weight training due to the proven benefits for muscle strength and hypertrophy using relatively low resistance, hence reducing the mechanical stress across a joint. As such, it has become an important part of rehabilitation programs used in either injured or operated athletes. Despite a general consensus on effectiveness of BFRR training for muscle conditioning, there are several uncertainties regarding the interplay of various extrinsic and intrinsic factors on its safety and efficiency, which are being reviewed from a clinical perspective. Among extrinsic factors tourniquet cuff pressure, size and shape have been identified as key for safety and efficiency. Among intrinsic factors, limb anthropometrics, patient history and presence of cardiac, vascular, metabolic or peripheral neurologic conditions have been recognized as most important. Though there are a few potential safety concerns connected to BFRR training, the following have been identified as the most probable and health-hazardous: (a mechanical injury to the skin, muscle, and peripheral nerves, (b venous thrombosis due to vascular damage and disturbed hemodynamics and (c augmented arterial blood pressure responses due to combined high body exertion and increased peripheral vascular resistance. Based on reviewed literature and authors’ personal experience with the use of BFRR training in injured athletes, some guidelines for its safe application are outlined. Also, a comprehensive risk assessment tool for screening of subjects prior to their inclusion in a BFRR training program is being introduced.

  16. Changes in maxillary molar pulp blood flow during orthodontic intrusion. (United States)

    Sabuncuoglu, Fidan Alakus; Ersahan, Seyda


    The aim of this prospective study was to evaluate the effects of maxillary first molar intrusion on pulpal blood flow (PBF) in humans as recorded by laser Doppler flowmetry (LDF). Maxillary first molars of 16 participants were divided into two groups. In the study group, 20 teeth in 10 participants were subjected to an intrusive force of 100 g delivered from mini-implants for 6 months. A control group of 6 subjects (12 teeth) received no orthodontic treatment. LDF measurements were recorded at baseline and at 3 days, 3 weeks, 3 months and 6 months during intrusion. Data was analysed using the Wilcoxon Signed Rank and Mann-Whitney U tests, with a level of p intrusion with mini-implants and an applied force of 100 g, blood vessel function was maintained throughout intrusion, as indicated by LDF measurements of PBF, which tended to return to baseline values by the end of the observation period. These results highlight the changes that can occur in molar vascularity, especially during six months of intrusion.

  17. Computational model of blood flow in the aorto-coronary bypass graft

    Directory of Open Access Journals (Sweden)

    Ghista Dhanjoo N


    Full Text Available Abstract Background Coronary artery bypass grafting surgery is an effective treatment modality for patients with severe coronary artery disease. The conduits used during the surgery include both the arterial and venous conduits. Long- term graft patency rate for the internal mammary arterial graft is superior, but the same is not true for the saphenous vein grafts. At 10 years, more than 50% of the vein grafts would have occluded and many of them are diseased. Why do the saphenous vein grafts fail the test of time? Many causes have been proposed for saphenous graft failure. Some are non-modifiable and the rest are modifiable. Non-modifiable causes include different histological structure of the vein compared to artery, size disparity between coronary artery and saphenous vein. However, researches are more interested in the modifiable causes, such as graft flow dynamics and wall shear stress distribution at the anastomotic sites. Formation of intimal hyperplasia at the anastomotic junction has been implicated as the root cause of long- term graft failure. Many researchers have analyzed the complex flow patterns in the distal sapheno-coronary anastomotic region, using various simulated model in an attempt to explain the site of preferential intimal hyperplasia based on the flow disturbances and differential wall stress distribution. In this paper, the geometrical bypass models (aorto-left coronary bypass graft model and aorto-right coronary bypass graft model are based on real-life situations. In our models, the dimensions of the aorta, saphenous vein and the coronary artery simulate the actual dimensions at surgery. Both the proximal and distal anastomoses are considered at the same time, and we also take into the consideration the cross-sectional shape change of the venous conduit from circular to elliptical. Contrary to previous works, we have carried out computational fluid dynamics (CFD study in the entire aorta-graft-perfused artery domain

  18. Proximal spleno-renal shunt with retro-aortic left renal vein in a patient with extra-hepatic portal vein obstruction: first case report. (United States)

    Jain, Sundeep; Kalla, Mukesh; Suleman, Adil; Verma, Alok


    Presence of retro-aortic left renal vein poses special challenge in creating spleno-renal shunt potentially increasing the chance of shunt failure. The technical feasibility and successful outcome of splenectomy with proximal spleno-renal shunt (PSRS) with retro-aortic left renal vein is presented for the first time. The patient was treated for portal hypertension and hypersplenism due to idiopathic extra-hepatic portal vein obstruction. A twenty year old male suffering from idiopathic extra-hepatic portal vein obstruction presented with bleeding esophageal varices, portal hypertensive gastropathy, asymptomatic portal biliopathy and symptomatic hypersplenism. As variceal bleeding did not respond to endoscopic and medical treatment, surgical portal decompression was planned. On preoperative contrast enhanced computed tomography retro-aortic left renal vein was detected. Splenectomy with proximal splenorenal shunt with retro-aortic left renal vein was successfully performed by using specific technical steps including adequate mobilisation of retro-aortic left renal vein and per-operative pressure studies. Perioperative course was uneventful and patient is doing well after 3 years of follow up. PSRS is feasible, safe and effective procedure when done with retro-aortic left renal vein for the treatment of portal hypertension related to extra-hepatic portal vein obstruction provided that attention is given to key technical considerations including pressure studies necessary to ensure effective shunt. Present case provides the first evidence that retro-aortic left renal vein can withstand the extra volume of blood flow through the proximal shunt with effective portal decompression so as to treat all the components of extra-hepatic portal vein obstruction without causing renal venous hypertension.

  19. Mannitol increases renal blood flow and maintains filtration fraction and oxygenation in postoperative acute kidney injury: a prospective interventional study (United States)


    Introduction Acute kidney injury (AKI), which is a major complication after cardiovascular surgery, is associated with significant morbidity and mortality. Diuretic agents are frequently used to improve urine output and to facilitate fluid management in these patients. Mannitol, an osmotic diuretic, is used in the perioperative setting in the belief that it exerts reno-protective properties. In a recent study on uncomplicated postcardiac-surgery patients with normal renal function, mannitol increased glomerular filtration rate (GFR), possibly by a deswelling effect on tubular cells. Furthermore, experimental studies have previously shown that renal ischemia causes an endothelial cell injury and dysfunction followed by endothelial cell edema. We studied the effects of mannitol on renal blood flow (RBF), glomerular filtration rate (GFR), renal oxygen consumption (RVO2), and extraction (RO2Ex) in early, ischemic AKI after cardiac surgery. Methods Eleven patients with AKI were studied during propofol sedation and mechanical ventilation 2 to 6 days after complicated cardiac surgery. All patients had severe heart failure treated with one (100%) or two (73%) inotropic agents and intraaortic balloon pump (36%). Systemic hemodynamics were measured with a pulmonary artery catheter. RBF and renal filtration fraction (FF) were measured by the renal vein thermo-dilution technique and by renal extraction of chromium-51-ethylenediaminetetraacetic acid (51Cr-EDTA), respectively. GFR was calculated as the product of FF and renal plasma flow RBF × (1-hematocrit). RVO2 and RO2Ex were calculated from arterial and renal vein blood samples according to standard formulae. After control measurements, a bolus dose of mannitol, 225 mg/kg, was given, followed by an infusion at a rate of 75 mg/kg/h for two 30-minute periods. Results Mannitol did not affect cardiac index or cardiac filling pressures. Mannitol increased urine flow by 61% (P Mannitol increased the RBF/cardiac output (CO

  20. Airway blood flow response to dry air hyperventilation in sheep

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, G.H.; Baile, E.M.; Pare, P.D.


    Airway blood flow (Qaw) may be important in conditioning inspired air. To determine the effect of eucapneic dry air hyperventilation (hv) on Qaw in sheep the authors studied 7 anesthetized open-chest sheep after 25 min. of warm dry air hv. During each period of hv the authors have recorded vascular pressures, cardiac output (CO), and tracheal mucosal and inspired air temperature. Using a modification of the reference flow technique radiolabelled microspheres were injected into the left atrium to make separate measurements after humid air and dry air hv. In 4 animals a snare around the left main pulmonary artery was used following microsphere injection to prevent recirculation (entry into L lung of microspheres from the pulmonary artery). Qaw to the trachea and L lung as measured and Qaw for the R lung was estimated. After the final injection the sheep were killed and bronchi (Br) and lungs removed. Qaw (trachea plus L lung plus R lung) in 4 sheep increased from a mean of 30.8 to 67.0 ml/min. Airway mucosal temp. decreased from 39/sup 0/ to 33/sup 0/C. The authors conclude that dry air hv cools airway mucosa and increases Qaw in sheep.

  1. Impact of mydriatic eye drops on neonatal cerebral blood flow

    Directory of Open Access Journals (Sweden)

    Atef Alshafei


    Full Text Available Retinopathy of prematurity (ROP screening is a common routine procedure carried out on preterm infants in neonatal intensive care units (NICUs. Mydriatic eye drops containing phenylephrine hydrochloride 2.5% (a sympathomimetic agent and tropicamide 0.5% (a cycloplegic medication are readily absorbed from the conjunctiva and produce systemic responses in various organs. To our knowledge, no studies have investigated the direct effects of these medications on cerebral blood flow velocities (CBFVs in preterm infants. To evaluate the systemic effects of locally instilled mydriatic eye drops (phenylephrine hydrochloride 2.5% and tropicamide 0.5% used for ROP screening, on cerebral blood flow velocity in preterm infants, a prospective observational study was conducted among preterm infants with gestational age (GA < 31 weeks admitted to the NICU at Dubai Hospital between February 20, 2017 and June 20, 2017. The infants (at a post-menstrual age of 31-34 weeks underwent duplex ultrasound evaluation of CBFV before and after mydriatic eye drops administration.Pulsed-wave Doppler ultrasound studies were performed 1 h before and 1 h after eye mydriasis. We measured peak systolic velocity (PSV and end diastolic velocity (EDV for both the anterior cerebral artery (ACA and middle cerebral artery (MCA and calculated the resistive index (RI, defined as PSV – EDV/PSV. Mean arterial blood pressure (MAP, heart rate, oxygen saturation and pain score were assessed before and 1 h after ROP examination.A paired t-test and McNemar’s test were used to assess the statistical significance of the difference between pairs of means and the qualitative variables measured twice for the same study group.Among the 42 eligible preterm infants, the mean (SD GA was 27 (2.68 weeks (range, 24-31 weeks. The mean (SD RI of ACA before and 1 h after eye drops administration was 0.84 (0.06 and 0.83 (0.07 respectively (p = 0.453. The mean (SD RIs of MCA before and then 1 h after

  2. Changes of time-attenuation curve blood flow parameters in patients with and without carotid stenosis. (United States)

    Lin, C-J; Chang, F-C; Guo, W-Y; Hung, S-C; Luo, C-B; Beilner, J; Kowarschik, M; Chu, W-F


    From the time-attenuation curves of DSA flow parameters, maximal intensity, maximal slope, and full width at half maximum of selected vascular points are defined. The study explores the reliability of defining the flow parameters by the time-attenuation curves of DSA. Seventy patients with unilateral carotid artery stenosis (group A) and 56 healthy controls (group B) were retrospectively enrolled. Fixed contrast injection protocols and DSA acquisition parameters were used with all patients. The M1, sigmoid sinus, and internal jugular vein on anteroposterior view DSA and the M2, parietal vein, and superior sagittal sinus on lateral view DSA were chosen as ROI targets for measuring flow parameters. The difference of time of maximal intensity between 2 target points was defined as the circulation time between the target points. The maximal intensity difference of 2 selected points from the ICA to the M1, sigmoid sinus, internal jugular vein, M2, parietal vein, and superior sagittal sinus was significantly longer in group A than in group B. The maximum slope of M1, M2, and the superior sagittal sinus was significantly lower in group A than in group B. The full width at half maximum of M1 and M2 was significantly larger in group A than in group B. The maximal slope of M1 demonstrated the best diagnostic performance. The maximal intensity difference of 2 selected points derived from DSA can be used as a definitive alternative flow parameter for intracranial circulation time measurement. Maximal slope and full width at half maximum complement the maximal intensity difference of 2 selected points in defining flow characteristics of healthy subjects and patients with carotid stenosis. © 2015 by American Journal of Neuroradiology.

  3. Mimicking the Interfacial Dynamics of Flowing White Blood Cells (United States)

    Santore, Maria


    The rolling of particles on surfaces, facilitated by hydrodynamic forces combined with localized surface interactions of the appropriate strengths, spatial arrangements, and ranges, is a technologically useful means of transporting and manipulating particles. One's intuition for the rolling of a marble or a car tire cannot be extrapolated down to microparticle length scales because the microparticle interactions are dominated by electrostatic, van der Waals, and hydrogen bonding interactions rather than a friction that depends on an imposed normal force. Indeed, our microparticle rolling systems are inspired by the rolling of white blood cells on the inner walls of venules as part of the innate immune response: Selectin molecules engage with their counterparts on the opposing surfaces to slow cell motion relative to that for freely flowing cells. In the resulting rolling signature, ligand-receptor binding and crack closing on the front of the cell are balanced with molecular dis-bonding and crack opening at the rear. The contact region is relatively static, allowing other interactions (for instance signaling) to occur for a finite duration. Thus, achieving particle rolling in synthetic systems is important because it facilitates particle-surface interactions in a continuous nonfouling fashion where the contact surface is continually renewed. In developing a synthetic model for this system, we employ polymers to modify flowing particles and /or planar collectors, producing heterogeneous interfaces which can support rolling or produce other motion signatures such as skipping, arrest, or free flow. We identify, in the synthetic system, combinations of variables that produce rolling and demonstrate how the distinction between rolling and arrest is not a simple matter of the adhesion strength between the particles and the collector. Rolling is a cooperative process and the coordination of binding in one location with dis-bonding in another requires appropriate length

  4. Skeletal blood flow in Paget's disease of bone and its response to calcitonin therapy. (United States)

    Wootton, R; Reeve, J; Spellacy, E; Tellez-Yudilevich, M


    1. Blood flow to the skeleton was measured by the 18F clearance method of Wooton, Reeve & Veall (1976) in 24 patients with untreated Paget's disease. In every patient but one, resting skeletal blood flow was increased. There was a significant positive correlation between skeletal blood flow and serum alkaline phosphatase and between skeletal blood flow and urinary total hydroxyproline excretion. 2. Fourteen patients were re-studied after they had received short-term (7 days or less) or long-term (7 weeks or more) calcitonin. Skeletal blood flow, alkaline phosphatase and urinary hydroxy-proline excretion fell towards normal in every case. There was some evidence from the short-term studies that calcitonin produced a more rapid fall in skeletal blood flow than in alkaline phosphatase. 3. Glomerular filtration rate appeared to increase transiently in response to calcitonin.

  5. Timing and topography of cerebral blood flow, aura, and headache during migraine attacks

    DEFF Research Database (Denmark)

    Olesen, J; Friberg, L; Olsen, T S


    Ten years of study has resulted in considerable but fragmented knowledge about regional cerebral blood flow in migraine with aura (classic migraine). In the present study, the number of repeatedly studied patients (n = 63) was large enough to determine statistically significant sequences of events...... and statistically significant spatial relations. The first observable event was a decrease of regional cerebral blood flow posteriorly in one cerebral hemisphere. Further development of this pathological process was accompanied by the aura symptoms. Thereafter headache occurred while regional cerebral blood flow...... remained decreased. During the headache phase, regional cerebral blood flow gradually changed from abnormally low to abnormally high without apparent change in headache. In some patients headache disappeared while regional cerebral blood flow remained increased. Although regional cerebral blood flow...

  6. Sympathetic reflex control of subcutaneous blood flow in tetraplegic man during postural changes

    DEFF Research Database (Denmark)

    Skagen, K; Jensen, K; Henriksen, O


    to the labelled area. Leg blood flow was unaltered by proximal blockade but could be blocked by local infiltration in the labelled area with lignocaine in low doses. 4. Head-up tilt of tetraplegic patients induced vasoconstriction in the subcutaneous tissue of the forearm, which could be prevented by proximal......1. The effect of head-up tilt upon subcutaneous blood flow in the distal arm and leg was studied in 12 patients with complete traumatic spinal cord transection at the cervical level. 2. Blood flow was measured by the local 133Xe washout technique. 3. Leg lowering induced a 47% decrease in blood...... flow in the distal leg. During head-up tilt (45 degrees) blood flow in the leg decreased by 48%. In the arm remaining at heart level blood flow decreased by 37% during tilt and this vasoconstriction could be prevented by nervous blockade with lignocaine injected subcutaneously 5 cm proximally...

  7. Analysis of chaotic and noise processes in a fluctuating blood flow using the Allan variance technique. (United States)

    Basarab, M A; Basarab, D A; Konnova, N S; Matsievskiy, D D; Matveev, V A


    The aim of this work was to develop a novel technique for digital processing of Doppler ultrasound blood flow sensor data from noisy blood flow velocity waveforms. To evaluate the fluctuating blood flow parameters, various nonlinear dynamics methods and algorithms are often being used. Here, for identification of chaotic and noise components in a fluctuating coronary blood flow, for the first time the Allan variance technique was used. Analysis of different types of noises (White, Brownian, Flicker) was carried out and their strong correlation with fractality of time series (the Hurst exponent) was revealed. Based on a specialized software realizing the developed technique, numerical experiments with real clinical data were carried out. Recommendations for identification of noisy patterns of coronary blood flow in normal and pathological states were developed. The methodology gives us the possibility for the more detailed quantitative and qualitative analysis of a noisy fluctuating blood flow data.

  8. Flow and oscillations in collapsible tubes: Physiological applications ...

    Indian Academy of Sciences (India)

    The motivation for this subject comes from physiology: Air-flow in the lungs, where flow limitation during forced expiration is a consequence of large-airway collapse, and wheezing, which is a manifestation of self-excited mechanical oscillations; Blood flow in veins, such as those of giraffes, in which the return of blood to the ...

  9. A comparison of Newtonian and non-Newtonian models for pulsatile blood flow simulations (United States)

    Husain, Iqbal; Labropulu, Fotini; Langdon, Chris; Schwark, Justin


    Mathematical modeling of blood flows in the arteries is an important and challenging problem. This study compares several non-Newtonian blood models with the Newtonian model in simulating pulsatile blood flow through two three-dimensional models of an arterial stenosis and an aneurysm. Four non-Newtonian blood models, namely the Power Law, the Casson, the Carreau, and the Generalized Power Law, as well as the Newtonian model of blood viscosity, are used to investigate the flow effects induced by these different blood constitutive equations. The aim of this study is three-fold: firstly, to investigate the variation in wall shear stress in an artery with a stenosis or aneurysm at different flow rates and degrees of severity; secondly, to compare the various blood models and hence quantify the differences between the models and judge their significance; and lastly, to determine whether the use of the Newtonian blood model is appropriate over a wide range of shear rates.

  10. Statistical dynamics of flowing red blood cells by morphological image processing.

    Directory of Open Access Journals (Sweden)

    John M Higgins


    Full Text Available Blood is a dense suspension of soft non-Brownian cells of unique importance. Physiological blood flow involves complex interactions of blood cells with each other and with the environment due to the combined effects of varying cell concentration, cell morphology, cell rheology, and confinement. We analyze these interactions using computational morphological image analysis and machine learning algorithms to quantify the non-equilibrium fluctuations of cellular velocities in a minimal, quasi-two-dimensional microfluidic setting that enables high-resolution spatio-temporal measurements of blood cell flow. In particular, we measure the effective hydrodynamic diffusivity of blood cells and analyze its relationship to macroscopic properties such as bulk flow velocity and density. We also use the effective suspension temperature to distinguish the flow of normal red blood cells and pathological sickled red blood cells and suggest that this temperature may help to characterize the propensity for stasis in Virchow's Triad of blood clotting and thrombosis.

  11. Mathematical Models and Numerical Simulations for the Blood Flow in Large Vessels


    Titus PETRILA; Balazs ALBERT


    We are proposing a non-Newtonian, Cross type rheological model for the blood flow, under the conditions of an unsteady flow regime connected with the rhythmic pumping of the blood by the heart. We admit the incompressibility and homogeneity of the blood while its flow is laminar and the exterior body forces are neglected. We take also into account the viscoelastic behavior of the vessel walls. The mathematical equations and the appropriate boundary conditions are considered in cylindrical (ax...

  12. Skin and muscle components of forearm blood flow in directly heated resting man. (United States)

    Detry, J.-M. R.; Brengelmann, G. L.; Rowell, L. B.; Wyss, C.


    Changes in forearm muscle blood flow (FMBF) during direct whole-body heating were measured in 17 normal subjects using three different methods. We conclude that FMBF is not increased by direct whole-body heating. Since renal and splanchnic blood flow fall 30% under these conditions, maximal total skin blood flow in 12 previously studied subjects can be estimated from the rise in cardiac output to be 7.6 L/min (3.0-11.1 L/min).

  13. Decreased skeletal muscle pump activity in patients with postural tachycardia syndrome and low peripheral blood flow. (United States)

    Stewart, Julian M; Medow, Marvin S; Montgomery, Leslie D; McLeod, Kenneth


    Standing translocates thoracic blood volume into the dependent body. The skeletal muscle pump participates in preventing orthostatic intolerance by enhancing venous return. We investigated the hypothesis that skeletal muscle pump function is impaired in postural tachycardia (POTS) associated with low calf blood flow (low-flow POTS) and depends in general on muscle blood flow. We compared 12 subjects that have low-flow POTS with 10 controls and 7 patients that have POTS and normal calf blood flow using strain-gauge plethysmography to measure peripheral blood flow, venous capacitance, and calf muscle pump function. Blood volume was estimated by dye dilution. We found that calf circumference was reduced in low-flow POTS (32 +/- 1 vs. 39 +/- 3 and 43 +/- 3 cm) and, compared with controls and POTS patients with normal blood flow, is related to the reduced fraction of calf venous capacity emptied during voluntary muscle contraction (ejection fraction, 0.52 +/- 0.07 vs. 0.76 +/- 0.07 and 0.80 +/- 0.06). We found that blood flow was linearly correlated (r(p) = 0.69) with calf circumference (used as a surrogate for muscle mass). Blood volume measurements were 2.2 +/- 0.3 in low-flow POTS vs. 2.6 +/- 0.5 in controls (P = 0.17) and 2.4 +/- 0.7 in normal-flow POTS patients. Decreased calf blood flow may reduce calf size in POTS and thereby impair the upright ejective ability of the skeletal muscle pump and further contribute to overall reduced blood flow and orthostatic intolerance in these patients.

  14. Face cooling with mist water increases cerebral blood flow during exercise: Effect of changes in facial skin blood flow

    Directory of Open Access Journals (Sweden)

    Taiki eMiyazawa


    Full Text Available Facial cooling (FC increases cerebral blood flow (CBF at rest and during exercise; however, the mechanism of this response remains unclear. The purpose of the present study was to test our hypothesis that FC causes facial vasoconstriction that diverts skin blood flow (SkBFface towards the middle cerebral artery (MCA Vmean at rest and to a greater extent during exercise. Nine healthy young subjects (20 ± 2 yrs. underwent 3 minutes of FC by fanning and spraying the face with a mist of cold water (~4˚C at rest and during steady-state exercise (heart rate of 120 bpm. We focused on the difference between the averaged data acquired from 1 min immediately before FC and last 1 min of FC. SkBFface, MCA Vmean and MAP were higher during exercise than at rest. As hypothesized, FC decreased SkBFface at rest (-32 ± 4 % and to a greater extent during exercise (-64 ± 10%, P=0.012. Although MCA Vmean was increased by FC (Rest, +1.4 ± 0.5 cm/s; Exercise, +1.4 ± 0.6 cm/s, the amount of the FC-evoked changes in MCA Vmean at rest and during exercise differed among subjects. In addition, changes in MCA Vmean with FC did not correlate with concomitant changes in SkBFface (r=0.095, P=0.709. MAP was also increased by FC (Rest, +6.2 ± 1.4 mmHg; Exercise, +4.2 ± 1.2 mmHg. These findings suggest that the FC induced increase in CBF during exercise could not be explained only by change in SkBFface.

  15. In vivo measurement of blood flow in a micro-scale stenosis model generated by laser photothermal blood coagulation. (United States)

    Lee, Sang Joon; Ha, Ho Jin


    Blood flow in a stenosed vessel is one of the most important issues, because it is closely related to the outbreak of circulatory diseases. To overcome the technological limitations encountered in the haemodynamic studies using in vitro stenosis models, the authors induced a stenosed flow model in the extraembryonic vessels of a chicken embryo. Blood was coagulated by laser irradiation to artificially form a stenosis on the designated spot in a straight blood vessel. Owing to photothermal coagulation of red blood cells (RBCs), the blood is denatured and a stable blood coagulum is induced in the vessel. The blood coagulum adheres firmly and stably on the vessel wall without any size variation. It disturbs the on-coming blood flow significantly. To investigate the haemodynamic characteristics of the blood flow in the stenosed vessel, a micro particle image velocimetry technique was employed using RBCs as tracers to measure the spatial distributions of velocity vectors, streamlines and shear rate. The present simple modelling of in vivo stenosis would be useful for investigating the basic haemodynamic mechanisms underlying circulatory vascular diseases.

  16. Modelling of the Blood Coagulation Cascade in an In Vitro Flow System

    DEFF Research Database (Denmark)

    Andersen, Nina Marianne; Sørensen, Mads Peter; Efendiev, Messoud A.


    We derive a mathematical model of a part of the blood coagulation cascade set up in a perfusion experiment. Our purpose is to simulate the influence of blood flow and diffusion on the blood coagulation pathway. The resulting model consists of a system of partial differential equations taking...... and flow equations, which guarantee non negative concentrations at all times. The criteria is applied to the model of the blood coagulation cascade....


    Directory of Open Access Journals (Sweden)

    Natalia I Kurysheva


    Full Text Available Purpose: to study the eye’s venous blood flow and the correlation between clinical data and ocular blood flow in normal tension and high tension open angle glaucoma (POAG. Methods: Color Doppler imaging of arterial and venous blood flow was performed on 78 patients with normal tension glaucoma (NTG, 80 patients with high-pressure glaucoma (HPG and 60 control subjects. The statistical analysis included the calculation of the correlation between clinical data and ocular blood flow parameters, as well as Pearson’s correlation coefficient. The threshold P value for statistical significance was 0.05. Results: Ocular blood flow (both arterial and venous was significantly reduced in NTG and HTG, compared to the control group. While the arterial blood flow reduction was more significant in HTG than in NTG, a decrease in venous blood flow had a higher incidence in NTG. In contrast to the control group, POAG patients showed a correlation between clinical data and venous blood flow. The correlation was higher in NTG patients. Conclusions: The results obtained indicate the potential importance of venous blood flow in glaucoma pathogenesis, especially in NTG.

  18. Uterine artery Doppler and subendometrial blood flow in patients with unexplained recurrent miscarriage

    Directory of Open Access Journals (Sweden)

    Hala Abdel Wahab


    Conclusion: The presence of good uterine and endometrial blood flow is an important prerequisite for successful implantation and continuation of pregnancy as shown by higher uterine artery blood flow resistance and lower endometrial blood flow in recurrent miscarriage cases and those patients with unexplained RPL may have abnormalities in the uterine and endometrial blood flow. Despite these findings we could not find any cut off values that could predict the occurrence of miscarriage which may be attributed to small sample size and short period of follow up so larger prospective studies are needed aiming to confirm such results and reaching values that can accurately predict the occurrence of miscarriage.

  19. Cerebral blood flow changes during sodium-lactate-induced panic attacks

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, R.S.; Devous, M.D. Sr.; Rush, A.J.; Lane, L.; Bonte, F.J.


    Dynamic single-photon emission computed axial tomography (CAT) with inhaled xenon-133 was used to measure regional cerebral blood flow in 10 drug-free patients with DSM-III-diagnosed panic disorder and in five normal control subjects. All subjects underwent regional cerebral blood flow studies while at rest or during normal saline infusion and during sodium lactate infusion. Six of the 10 patients and none of the control subjects experienced lactate-induced panic attacks. Lactate infusion markedly raised hemispheric blood flow levels in both control subjects and patients who did not panic. Patients who did panic experienced either a minimal increase or a decrease in hemispheric blood flow.

  20. Forearm Skin Blood Flow After Kinesiology Taping in Healthy Soccer Players: An Exploratory Investigation

    National Research Council Canada - National Science Library

    Woodward, Kirsty A; Unnithan, Vish; Hopkins, Nicola D


    Kinesiology tape (KT) has become popular among athletes for both injury prevention and rehabilitation due to its reported therapeutic effects, including facilitation of lymphatic flow and enhanced peripheral blood flow...

  1. In vivo vascular flow profiling combined with optical tweezers based blood routing (United States)

    Meissner, Robert; Sugden, Wade W.; Siekmann, Arndt F.; Denz, Cornelia


    In vivo wall shear rate is quantified during zebrafish development using particle image velocimetry for biomedical diagnosis and modeling of artificial vessels. By using brightfield microscopy based high speed video tracking we can resolve single heart-beat cycles of blood flow in both space and time. Maximum blood flow velocities and wall shear rates are presented for zebrafish at two and three days post fertilization. By applying biocompatible optical tweezers as an Optical rail we present rerouting of red blood cells in vivo. With purely light-driven means we are able to compensate the lack of proper red blood cell blood flow in so far unperfused capillaries.

  2. Transcranial Doppler-determined change in posterior cerebral artery blood flow velocity does not reflect vertebral artery blood flow during exercise. (United States)

    Washio, Takuro; Sasaki, Hiroyuki; Ogoh, Shigehiko


    We examined whether a change in posterior cerebral artery flow velocity (PCAv) reflected the posterior cerebral blood flow in healthy subjects during both static and dynamic exercise. PCAv and vertebral artery (VA) blood flow, as an index of posterior cerebral blood flow, were continuously measured during an exercise trial using transcranial Doppler (TCD) ultrasonography and Doppler ultrasound, respectively. Static handgrip exercise significantly increased both PCAv and VA blood flow. Increasing intensity of dynamic exercise further increased VA blood flow from moderate exercise, while PCAv decreased to almost resting level. During both static and dynamic exercise, the PCA cerebrovascular conductance (CVC) index significantly decreased from rest (static and high-intensity dynamic exercise, -11.5 ± 12.2% and -18.0 ± 16.8%, means ± SD, respectively) despite no change in the CVC of VA. These results indicate that vasoconstriction occurred at PCA but not VA during exercise-induced hypertension. This discrepancy in vascular response to exercise between PCA and VA may be due to different cerebral arterial characteristics. Therefore, to determine the effect of exercise on posterior cerebral circulation, at least, we need to carefully consider which cerebral artery to measure, regardless of exercise mode.NEW & NOTEWORTHY We examined whether transcranial Doppler-determined flow velocity in the posterior cerebral artery can be used as an index of cerebral blood flow during exercise. However, the changes in posterior cerebral artery flow velocity during exercise do not reflect vertebral artery blood flow. Copyright © 2017 the American Physiological Society.

  3. Numerical Modeling of Interstitial Fluid Flow Coupled with Blood Flow through a Remodeled Solid Tumor Microvascular Network.

    Directory of Open Access Journals (Sweden)

    M Soltani

    Full Text Available Modeling of interstitial fluid flow involves processes such as fluid diffusion, convective transport in extracellular matrix, and extravasation from blood vessels. To date, majority of microvascular flow modeling has been done at different levels and scales mostly on simple tumor shapes with their capillaries. However, with our proposed numerical model, more complex and realistic tumor shapes and capillary networks can be studied. Both blood flow through a capillary network, which is induced by a solid tumor, and fluid flow in tumor's surrounding tissue are formulated. First, governing equations of angiogenesis are implemented to specify the different domains for the network and interstitium. Then, governing equations for flow modeling are introduced for different domains. The conservation laws for mass and momentum (including continuity equation, Darcy's law for tissue, and simplified Navier-Stokes equation for blood flow through capillaries are used for simulating interstitial and intravascular flows and Starling's law is used for closing this system of equations and coupling the intravascular and extravascular flows. This is the first study of flow modeling in solid tumors to naturalistically couple intravascular and extravascular flow through a network. This network is generated by sprouting angiogenesis and consisting of one parent vessel connected to the network while taking into account the non-continuous behavior of blood, adaptability of capillary diameter to hemodynamics and metabolic stimuli, non-Newtonian blood flow, and phase separation of blood flow in capillary bifurcation. The incorporation of the outlined components beyond the previous models provides a more realistic prediction of interstitial fluid flow pattern in solid tumors and surrounding tissues. Results predict higher interstitial pressure, almost two times, for realistic model compared to the simplified model.

  4. Improving left ventricular segmentation in four-dimensional flow MRI using intramodality image registration for cardiac blood flow analysis. (United States)

    Gupta, Vikas; Bustamante, Mariana; Fredriksson, Alexandru; Carlhäll, Carl-Johan; Ebbers, Tino


    Assessment of blood flow in the left ventricle using four-dimensional flow MRI requires accurate left ventricle segmentation that is often hampered by the low contrast between blood and the myocardium. The purpose of this work is to improve left-ventricular segmentation in four-dimensional flow MRI for reliable blood flow analysis. The left ventricle segmentations are first obtained using morphological cine-MRI with better in-plane resolution and contrast, and then aligned to four-dimensional flow MRI data. This alignment is, however, not trivial due to inter-slice misalignment errors caused by patient motion and respiratory drift during breath-hold based cine-MRI acquisition. A robust image registration based framework is proposed to mitigate such errors automatically. Data from 20 subjects, including healthy volunteers and patients, was used to evaluate its geometric accuracy and impact on blood flow analysis. High spatial correspondence was observed between manually and automatically aligned segmentations, and the improvements in alignment compared to uncorrected segmentations were significant (P flow analysis from manual and automatically corrected segmentations did not differ significantly (P > 0.05). Our results demonstrate the efficacy of the proposed approach in improving left-ventricular segmentation in four-dimensional flow MRI, and its potential for reliable blood flow analysis. Magn Reson Med 79:554-560, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  5. Blood flow restriction exercise in sprinters and endurance runners. (United States)

    Takada, Shingo; Okita, Koichi; Suga, Tadashi; Omokawa, Masashi; Morita, Noriteru; Horiuchi, Masahiro; Kadoguchi, Tomoyasu; Takahashi, Masashige; Hirabayashi, Kagami; Yokota, Takashi; Kinugawa, Shintaro; Tsutsui, Hiroyuki


    We demonstrated that blood flow restriction (BFR) remarkably enhances muscular metabolic stress in resistance exercise, although there is a wide range of individual differences in the responses. It is possible that these differences could be due to training status and muscular physiological characteristics. We investigated intramuscular metabolic responses during low-intensity resistance exercise with BFR between two different types of track athletes. Twelve age-matched male track athletes (sprinter group, n = 6; endurance runner group, n = 6) were recruited and performed unilateral plantarflexion (30 repetitions per minute). The exercise protocols were as follows: low-intensity exercise at 20% of one-repetition maximum (1RM) (L), high-intensity exercise at 65% 1RM without BFR (1.3 times of systolic blood pressure), L with BFR for 2 min (L-BFR), and prolonged exercise time in L-BFR for 3 min (prolonged BFR). Metabolic stress, defined as phosphocreatine and intramuscular pH decrease, and muscle fiber recruitment were evaluated using P magnetic resonance spectroscopy. Endurance runners showed higher peak oxygen uptake and lower muscle strength than sprinters. Phosphocreatine decreases in endurance runners during exercise with BFR protocols were significantly greater than those in sprinters (P sprinters (P < 0.05). The changes in intramuscular pH and the incidence of fast-twitch fiber recruitment did not show a statistical difference between the two groups. Phosphocreatine decreases in L-BFR were significantly correlated with peak oxygen uptake (P < 0.05). The effects of low-intensity resistance exercise with BFR are greater in endurance runners according to higher aerobic capacity.

  6. Short-term effects of intravitreal triamcinolone acetonide injection on ocular blood flow evaluated with color Doppler ultrasonography

    Directory of Open Access Journals (Sweden)

    Mustafa Alpaslan Anayol


    Full Text Available AIM:To evaluate the changes in ocular blood flow with color Doppler ultrasonography (CDU after intravitreal triamcinolone acetonide (IVTA injection.METHODS: A total of 46 patients who underwent IVTA (4 mg/0.1 mL injection for diabetic macular edema (DME (n=22, central retinal vein occlusion (CRVO (n=12 and choroidal neovascular membrane (CNVM (n=12 were included in the study. Peak systolic velocity (PSV, end diastolic velocity (EDV and resistivity index (RI were measured from the ophthalmic artery (OA, the central retinal artery (CRA and the posterior ciliary artery (PCA of each patient with CDU before, at the end of the first week and at the end of the first month following IVTA injection.RESULTS:In the DME group, PSV of OA at the first of the first month (mean±SD (37.48±10.87 cm/s increased compared to pre-injection value (31.39±10.84 cm/s (P=0.048. There was a statistically significant decrease (P=0.049 in PSV of CRA at the end of the first month (7.97±2.67 cm/s compared to the pre-injection (9.47±3.37 cm/s. There was not any statistically significant difference on the other parameters in the DME group. Also, there was not any statistically significant difference on the ocular blood flow values in the CRVO and CNVM groups.CONCLUSION: We observed that 4 mg/0.1 mL IVTA increased PSV of OA and decreased PSV of CRA in DME patients and did not have any effect on ocular blood flow values of CRVO and CNVM patients.

  7. Cu-blood flow model through a catheterized mild stenotic artery with a thrombosis. (United States)

    Elnaqeeb, Thanaa; Mekheimer, Khaled S; Alghamdi, Felwah


    Copper nanoparticles blood flow analysis through a catheterized mild stenotic artery with a thrombosis is presented. The system of coupled governing equations are prescribed and then simplified under mild stenosis assumptions. The governing equations are solved exactly, and then expressions for temperature, axial velocity, stream function, wall shear stress and resistance impedance are obtained generally for metallic nanoparticles blood flow. Due to the importance of copper nanoparticles in biomedicine, the results for Cu-blood flow model are introduced. The effect of various pertinent flow and geometric parameters on copper-blood flow features in the stenotic region are illustrated and discussed through graphs for catheter and tube models. Blood trapping is introduced graphically for numerous flow parameters. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Diet-induced changes in subcutaneous adipose tissue blood flow in man

    DEFF Research Database (Denmark)

    Simonsen, L; Bülow, J; Astrup, A


    The effect of a carbohydrate-rich meal on subcutaneous adipose tissue blood flow was studied with and without continuous i.v. infusion of propranolol in healthy volunteers. The subcutaneous adipose tissue blood flow was measured with the 133Xe washout method in three different locations: the fore......The effect of a carbohydrate-rich meal on subcutaneous adipose tissue blood flow was studied with and without continuous i.v. infusion of propranolol in healthy volunteers. The subcutaneous adipose tissue blood flow was measured with the 133Xe washout method in three different locations......: the forearm, the thigh and the abdomen. The subjects were given a meal consisting of white bread, jam, honey and apple juice (about 2300 kJ). The meal induced a twofold increase in blood flow in the examined tissues. Propranolol abolished the flow increase in the thigh and the abdomen and reduced...

  9. Analysis of Systolic Backflow and Secondary Helical Blood Flow in the Ascending Aorta Using Vector Flow Imaging

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Møller-Sørensen, Hasse; Kjaergaard, Jesper


    Secondary rotational flow and systolic backflow are seen in the ascending aorta and, in this study, were analyzed with the vector velocity method transverse oscillation. Twenty-five patients were scanned intra-operatively, and the vector velocities were related to estimates of transesophageal.......001) and the duration and flow direction of the secondary flow (p indicates...... that backflow is injurious and that secondary flow is a normal flow phenomenon. The study also shows that transverse oscillation can provide new information on blood flow in the ascending aorta....

  10. The Effects of Blood Flow Restricted Electrostimulation on Strength & Hypertrophy. (United States)

    Slysz, Joshua; Burr, Jamie F


    The combined effect of neuromuscular electrical muscle stimulation (NMES) and blood flow restriction (BFR) on muscle mass and strength has not been thoroughly investigated. To examine the effects of combined and independent BFR and a low-intensity NMES on skeletal muscle adaptation. Exploratory Study. Laboratory. Twenty recreationally active subjects. Subjects had each leg randomly allocated to one of four possible intervention groups: 1) cyclic BFR alone 2) NMES alone 3) BFR+NMES (COMB), or 4) control (CON). Each leg was stimulated in its respective intervention group for 32 minutes, 4d/wk for six weeks. Mean differences in size (g) and isometric strength (kg), between week 0 and week 6, were calculated for each group. Leg strength increased 32±19 kg in the COMB group, which differed from the 3±11kg change in the CON group (p=0.03). The isolated NMES and BFR groups revealed increases of 16±28kg and 18±17kg, respectively, but these did not statistically differ from the control, or one another. No alterations were statistically significant for leg size. Compared to a control that received no treatment, the novel combination of BFR and NMES led to increasing muscular strength of the knee extensors, but not muscle mass which had a large inter-individual variability in response.

  11. Alcohol Consumption and Cerebral Blood Flow Among Older Adults (United States)

    Christie, Israel C.; Price, Julie; Edwards, Louisa; Muldoon, Matthew; Meltzer, Carolyn C.; Jennings, J. Richard


    A substantial epidemiological literature now supports the existence of a J- or U-shaped association between alcohol consumption and a broad range cardiovascular health outcomes including stroke. Although it is well documented that alcoholics exhibit both global and regional cerebral hypoperfusion in the sober state, little is known regarding the effects of a broader range of alcohol consumption on cerebral blood flow (CBF). The present study employed positron emission tomography with H215O to assess quantitative global and regional CBF in 86 participants (51 men and 35 women; mean age 60.1) as a function of self-reported weekly alcohol consumption (none, 15 drinks per week). Analyses controlling for age, gender, and vascular health (carotid intima-media thickness) revealed that, relative to the weighted population mean, global CBF was greater in the lightest alcohol consumption group (15 per week). Effects did not vary across regions of interest. This report is the first to describe an inverted J-shaped relationship between alcohol consumption and CBF in the absence of stroke. PMID:18539247

  12. Alcohol consumption and cerebral blood flow among older adults. (United States)

    Christie, Israel C; Price, Julie; Edwards, Louisa; Muldoon, Matthew; Meltzer, Carolyn C; Jennings, J Richard


    A substantial epidemiological literature now supports the existence of a J or U-shaped association between alcohol consumption and a broad range cardiovascular health outcomes including stroke. Although it is well documented that alcoholics exhibit both global and regional cerebral hypoperfusion in the sober state, little is known regarding the effects of a broader range of alcohol consumption on cerebral blood flow (CBF). The present study employed positron emission tomography with H(2)(15)O to assess quantitative global and regional CBF in 86 participants (51 men and 35 women; mean age 60.1) as a function of self-reported weekly alcohol consumption (none, 15 drinks per week). Analyses controlling for age, gender, and vascular health (carotid intima-media thickness) revealed that, relative to the weighted population mean, global CBF was greater in the lightest alcohol consumption group (15 per week). Effects did not vary across regions of interest. This report is the first to describe an inverted J-shaped relationship between alcohol consumption and CBF in the absence of stroke.

  13. Numerical method of characteristics for one-dimensional blood flow (United States)

    Acosta, Sebastian; Puelz, Charles; Rivière, Béatrice; Penny, Daniel J.; Rusin, Craig G.


    Mathematical modeling at the level of the full cardiovascular system requires the numerical approximation of solutions to a one-dimensional nonlinear hyperbolic system describing flow in a single vessel. This model is often simulated by computationally intensive methods like finite elements and discontinuous Galerkin, while some recent applications require more efficient approaches (e.g. for real-time clinical decision support, phenomena occurring over multiple cardiac cycles, iterative solutions to optimization/inverse problems, and uncertainty quantification). Further, the high speed of pressure waves in blood vessels greatly restricts the time step needed for stability in explicit schemes. We address both cost and stability by presenting an efficient and unconditionally stable method for approximating solutions to diagonal nonlinear hyperbolic systems. Theoretical analysis of the algorithm is given along with a comparison of our method to a discontinuous Galerkin implementation. Lastly, we demonstrate the utility of the proposed method by implementing it on small and large arterial networks of vessels whose elastic and geometrical parameters are physiologically relevant.

  14. Modelling retinal pulsatile blood flow from video data. (United States)

    Betz-Stablein, Brigid; Hazelton, Martin L; Morgan, William H


    Modern day datasets continue to increase in both size and diversity. One example of such 'big data' is video data. Within the medical arena, more disciplines are using video as a diagnostic tool. Given the large amount of data stored within a video image, it is one of most time consuming types of data to process and analyse. Therefore, it is desirable to have automated techniques to extract, process and analyse data from video images. While many methods have been developed for extracting and processing video data, statistical modelling to analyse the outputted data has rarely been employed. We develop a method to take a video sequence of periodic nature, extract the RGB data and model the changes occurring across the contiguous images. We employ harmonic regression to model periodicity with autoregressive terms accounting for the error process associated with the time series nature of the data. A linear spline is included to account for movement between frames. We apply this model to video sequences of retinal vessel pulsation, which is the pulsatile component of blood flow. Slope and amplitude are calculated for the curves generated from the application of the harmonic model, providing clinical insight into the location of obstruction within the retinal vessels. The method can be applied to individual vessels, or to smaller segments such as 2 × 2 pixels which can then be interpreted easily as a heat map. © The Author(s) 2016.

  15. Cerebral blood flow associated with creative performance: a comparative study. (United States)

    Chávez-Eakle, Rosa Aurora; Graff-Guerrero, Ariel; García-Reyna, Juan-Carlos; Vaugier, Víctor; Cruz-Fuentes, Carlos


    Creativity is important for social survival and individual wellbeing; science, art, philosophy and technology have been enriched and expanded by this trait. To our knowledge this is the first study probing differences in brain cerebral blood flow (CBF) between highly creative individuals (scientists and/or artists socially recognized for their contributions to their fields with creativity indexes corresponding to the 99% percentile) and average control subjects while performing a verbal task from the Torrance Tests of Creative Thinking. Additionally, we correlated CBF with creativity dimensions such as fluency, originality and flexibility. Subjects with a high creative performance showed greater CBF activity in right precentral gyrus, right culmen, left and right middle frontal gyrus, right frontal rectal gyrus, left frontal orbital gyrus, and left inferior gyrus (BA 6, 10, 11, 47, 20), and cerebellum; confirming bilateral cerebral contribution. These structures have been involved in cognition, emotion, working memory, and novelty response. The score on the three creativity dimensions--fluency, originality, and flexibility--correlated with CBF activation in right middle frontal gyrus and right rectal gyrus (Brodmann Area 6, 11). Moreover, fluency and flexibility strongly correlated with CBF in left inferior frontal gyrus and originality correlated with CBF in left superior temporal gyrus and cerebellar tonsil. These findings suggest an integration of perceptual, volitional, cognitive and emotional processes in creativity. The higher CBF found in particular brain regions of highly creative individuals during the performance of a creative task provides evidence of a specific neural network related to the creative process.

  16. Altered Regional Cerebral Blood Flow in Chronic Whiplash Associated Disorders

    Directory of Open Access Journals (Sweden)

    David Vállez García


    Full Text Available There is increasing evidence of central hyperexcitability in chronic whiplash-associated disorders (cWAD. However, little is known about how an apparently simple cervical spine injury can induce changes in cerebral processes. The present study was designed (1 to validate previous results showing alterations of regional cerebral blood flow (rCBF in cWAD, (2 to test if central hyperexcitability reflects changes in rCBF upon non-painful stimulation of the neck, and (3 to verify our hypothesis that the missing link in understanding the underlying pathophysiology could be the close interaction between the neck and midbrain structures. For this purpose, alterations of rCBF were explored in a case-control study using H215O positron emission tomography, where each group was exposed to four different conditions, including rest and different levels of non-painful electrical stimulation of the neck. rCBF was found to be elevated in patients with cWAD in the posterior cingulate and precuneus, and decreased in the superior temporal, parahippocampal, and inferior frontal gyri, the thalamus and the insular cortex when compared with rCBF in healthy controls. No differences in rCBF were observed between different levels of electrical stimulation. The alterations in regions directly involved with pain perception and interoceptive processing indicate that cWAD symptoms might be the consequence of a mismatch during the integration of information in brain regions involved in pain processing.

  17. Comparative evaluation of pulpal blood flow during incisor intrusion. (United States)

    Sabuncuoglu, Fidan Alakus; Ersahan, Seyda


    The aim of the present study was to evaluate and compare changes in pulpal blood flow (PBF) as a result of maxillary incisor intrusion achieved by one of two methods (utility arches or mini-implants). Thirty subjects were divided into three groups, the first of which underwent maxillary incisor intrusion using utility arches (UA) and a second group, intrusion via mini-implants (MI). The third group acted as a control. An intrusive force of 100 g was applied to the upper incisors in the treatment groups, whereas no force was applied to the anterior teeth in the control group. A laser Doppler flowmeter (LDF) was used to measure PBF at baseline (T0) and during incisor intrusion at 24 hours (T1), three days (T2), seven days (T3) and three weeks (T4). Statistical changes in PBF were assessed by the Wilcoxon Signed Rank and Mann-Whitney U tests, with significance set at p intrusion at T4. No significant changes in PBF were observed in the control group over the course of the study. The only statistically significant difference between the UA and MI groups were at T1 and T2, at which time the MI group had lower PBF values (p intrusion methods are reversible. Although the changes in PBF could not be directly related to the method of intrusion employed, in general, a more severe drop in PBF was observed in the MI group during the first three days of intrusion.

  18. Cerebral blood flow during static exercise in humans

    DEFF Research Database (Denmark)

    Rogers, H B; Schroeder, T; Secher, N H


    resistance increased from 1.5 (1.0-2.2) to 2.4 (1.4-3.0) mmHg. 100 (P less than 0.025) at 32% of MVC. There was no difference in CBF between the two hemispheres at rest or during exercise. In contrast to dynamic leg exercise, static leg exercise is not associated with an increase in global CBF......Cerebral blood flow (CBF) was determined in humans at rest and during four consecutive unilateral static contractions of the knee extensors. Each contraction was maintained for 3 min 15 s with the subjects in a semisupine position. The contractions corresponded to 8, 16, 24, and 32% of the maximal...... (102-146) mmHg, respectively (P less than 0.0005), during the contraction at 32% MVC. Arterial PCO2 and central venous pressure did not change. Corrected to the average resting PCO2, CBF during control was 55 (35-73) ml.100 g-1.min-1 and remained constant during contractions. Cerebral vascular...

  19. In vivo cerebral blood flow autoregulation studies using rheoencephalography (United States)

    Bodo, M.; Pearce, F.; Garcia, A.; Van Albert, S.; Settle, T.; Szebeni, J.; Baranyi, L.; Hartings, J.; Armonda, R.


    Acute management of patients with traumatic brain/blast injury is a challenge. To minimize secondary injury and improve outcome, it is critical to detect neurological deterioration early, when it is potentially reversible. One potential monitoring method is cerebral electrical impedance (rheoencephalography-REG) because of its non-invasiveness and good time resolution. Reported here are the results of cerebral blood flow (CBF) manipulations comparing electroencephalogram (EEG) with REG (both intra-cerebral) and measuring with surface and skull REG electrodes. Our hypothesis was that REG would reflect spreading depression and CBF autoregulation. Animal experiments were performed using one rat (four trials with intracerebral electrodes), monkeys (n=8, with surface electrodes) and pigs (n = 24 pigs with skull electrodes; 57 trials, 19 types of liposomes). Challenges included intracranial pressure (ICP) elevation, liposome infusion, and hemorrhage. Data were stored on a PC and evaluated off line. CBF autoregulation was evaluated both by visual inspection and by a Matlab script. These studies confirmed that REG reflects CBF autoregulation and that REG is useful for detecting spreading depression (SD), vasospasm and the lower limit of CBF autoregulation. These findings have clinical relevance for use in noninvasive neuro-monitoring in the neurosurgery intensive care and during transportation of patients with brain injury.

  20. Dual-lumen catheters for continuous venovenous hemofiltration: limits for blood delivery via femoral vein access and a potential alternative in an experimental setting in anesthetized pigs


    Unger, Juliane K; Pietzner, Klaus; Francis, Roland C; Birnbaum, Juergen; Theisen, Marc Michael; Lemke, Arne-Joern; Niehues, Stefan M


    Introduction Small intravascular volume, pathophysiological hemorheology, and/or low cardiac output [CO] are assumed to reduce available blood flow rates via common dual-lumen catheters (except for those with a right atrium catheter tip position) in the critically ill patient. We performed an experimental animal study to verify these assumptions. Methods Anesthetized, ventilated pigs (35 to 50 kg) were allocated to different hemorheological conditions based on the application of different vol...

  1. Transient Non-Newtonian Blood Flow under Magnetic Targeting Drug Delivery in an Aneurysm Blood Vessel with Porous Walls (United States)

    Alimohamadi, Haleh; Imani, Mohsen


    The present investigation deals with numerical solution of blood flow patterns through an aneurysm artery under the applied magnetic field. Transient extended Navier-Stokes, Brinkman, continuity, and heat conduction equations govern this phenomenon and unsteady pulsatile inlet velocity varies by human heart-beating frequency. Our simulation demonstrates applying 105 magnetic field intensity (MnF) to recirculate flow and increase fluid flux and maximum blood temperature by 62.5x and 3.5%, respectively, in the aneurysm region. It is also shown that the vessel's wall porosity plays an important role in magnetic targeting of drug delivery performance, as this parameter can noticeably change maximum blood temperature and pressure.

  2. Varicose veins (United States)

    ... swelling. These stockings gently squeeze your legs to move blood up towards your heart. DO NOT sit or stand ... can help you keep off weight and help move blood up your legs. Walking or swimming are good options. ...

  3. Testing a new surfactant in a widely-used blood mimic for ultrasound flow imaging. (United States)

    Zhou, Xiaowei; Hoskins, Peter R


    A blood-mimicking fluid developed by Ramnarine et al. has been widely used in flow phantoms for ultrasound flow imaging research, and it has also been cited by IEC 61685 as a reference for making blood-mimicking fluid.However, the surfactant material Synperonic N in this blood-mimicking fluid recipe is phased out from the European market due to environmental issues. The aim of this study is to test whether Synperonic N can be substituted by biodegradable Synperonic A7 in making blood-mimicking fluid for ultrasound flow imaging research. A flow phantom was fabricated to test the blood-mimicking fluid with Synperonic N and Synperonic A7 as surfactants separately. Doppler images and velocity data were collected using a clinical ultrasound scanner under constant and pulsatile flows; and images and measured velocities were compared. It was found that both blood mimics can provide exactly the same images under spectral Doppler ultrasound and colour Doppler ultrasound in terms of their image qualities. The maximum velocities under constant flow were measured by the spectral Doppler ultrasound as 0.4714 ± 0.001 m.s-1 and 0.4644 ± 0.001 m.s-1 for blood-mimicking fluid with Synperonic N and blood-mimicking fluid with Synperonic A7, respectively. Measured velocities using the two different blood-mimicking fluids were statistically different (p flow imaging research.

  4. Adrenergic influence on gastric mucosal blood flow in gastric fistula dogs

    DEFF Research Database (Denmark)

    Hovendal, C P; Bech, K; Gottrup, F


    The aim of this study was to examine the influence of alpha-, beta- and dopaminergic receptors on gastric mucosal blood flow during "high", "normal", and "low" vagal conditions obtained by stimulation with bethanechol and pentagastrin and by parietal cell vagotomy respectively. During pentagastri...... increasing effect on mucosal blood flow. One may conclude that blood flow and acid secretion are not unconditionally linked and that at least two different mechanisms are involved in blood flow changes in the stomach.(ABSTRACT TRUNCATED AT 250 WORDS)...... and bethanechol stimulation, a linear relationship between gastric acid secretion and mucosal blood flow was observed. During pentagastrin stimulation, dopamine (40 micrograms/kg/min) did not change the blood flow values while a decrease in acid secretion was found. During bethanechol stimulation dopamine (10...... micrograms/kg/min) induced an increase in mucosal blood flow and a similar increase in acid secretion. If the dopamine infusion was preceded by alpha-receptor blockade, a pronounced increase in mucosal blood flow was observed without a similar increase in acid secretion. beta-adrenergic stimulation...

  5. Changes in interstitial K+ and pH during exercise: implications for blood flow regulation

    DEFF Research Database (Denmark)

    Juel, Carsten


    that blood flow is affected by changes in K+ as low as 0.1 mmol/L. The vasodilatory effect of K+ can be inhibited with simultaneous barium infusion, indicating that inward rectifier potassium (Kir)channels are involved. Acidosis has a direct effect on blood flow and an indirect effect, mediated by changes...

  6. Vascular Function and Regulation of Blood Flow in Resting and Contracting Skeletal Muscle

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin

    The precise matching of blood flow, oxygen delivery and metabolism is essential as it ensures that any increase in muscle work is precisely matched by increases in oxygen delivery. Therefore, understanding the control mechanisms of skeletal muscle blood flow regulation is of great biological impo...

  7. Cerebral oxygen extraction, oxygen consumption, and regional cerebral blood flow during the aura phase of migraine

    DEFF Research Database (Denmark)

    Friberg, L; Olesen, Jes; Lassen, N A


    The aura phase of migraine is associated with focal blood flow changes, but it has been largely unknown whether these changes are correlated to changes in the cerebral metabolism.......The aura phase of migraine is associated with focal blood flow changes, but it has been largely unknown whether these changes are correlated to changes in the cerebral metabolism....

  8. Blood flow response to electrically induced twitch and tetanic lower-limb muscle contractions.

    NARCIS (Netherlands)

    Janssen, T.W.; Hopman, M.T.E.


    OBJECTIVES: To compare the effect of electric stimulation (ES)-induced twitch with tetanic leg muscle contractions on blood flow responses and to assess blood flow responses in the contralateral inactive leg. DESIGN: Intervention with within-subject comparisons. SETTING: University research

  9. Blood flow response to electrically induced twitch and tetanic lower-limb muscle contractions

    NARCIS (Netherlands)

    Janssen, T.W.J.; Hopman, M.T.E.


    Objectives: To compare the effect of electric stimulation (ES)-induced twitch with tetanic leg muscle contractions on blood flow responses and to assess blood flow responses in the contralateral inactive leg. Design: Intervention with within-subject comparisons. Setting: University research

  10. Transcranial Doppler estimation of cerebral blood flow and cerebrovascular conductance during modified rebreathing.

    NARCIS (Netherlands)

    Claassen, J.A.H.R.; Zhang, R.; Fu, Q.; Witkowski, S.; Levine, B.D.


    Clinical transcranial Doppler assessment of cerebral vasomotor reactivity (CVMR) uses linear regression of cerebral blood flow velocity (CBFV) vs. end-tidal CO(2) (Pet(CO(2))) under steady-state conditions. However, the cerebral blood flow (CBF)-Pet(CO(2)) relationship is nonlinear, even for

  11. Quantitative evaluation of myocardial function by a volume-normalized map generated from relative blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Fukami, Tadanori [Department of Bio-system Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Sato, Hidenori [Department of Bio-system Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Wu, Jin [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Lwin, Thet-Thet- [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Yuasa, Tetsuya [Department of Bio-system Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Kawano, Satoru [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Iida, Keiji [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Akatsuka, Takao [Department of Bio-system Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Hontani, Hidekata [Department of Computer Science and Engineering, Nagoya Institute of Technology, Aichi 466-8555 (Japan); Takeda, Tohoru [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Tamura, Masao [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Yokota, Hiroshi [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan)


    Our study aimed to quantitatively evaluate blood flow in the left ventricle (LV) of apical hypertrophic cardiomyopathy (APH) by combining wall thickness obtained from cardiac magnetic resonance imaging (MRI) and myocardial perfusion from single-photon emission computed tomography (SPECT). In this study, we considered paired MRI and myocardial perfusion SPECT from ten patients with APH and ten normals. Myocardial walls were detected using a level set method, and blood flow per unit myocardial volume was calculated using 3D surface-based registration between the MRI and SPECT images. We defined relative blood flow based on the maximum in the whole myocardial region. Accuracies of wall detection and registration were around 2.50 mm and 2.95 mm, respectively. We finally created a bull's-eye map to evaluate wall thickness, blood flow (cardiac perfusion) and blood flow per unit myocardial volume. In patients with APH, their wall thicknesses were over 10 mm. Decreased blood flow per unit myocardial volume was detected in the cardiac apex by calculation using wall thickness from MRI and blood flow from SPECT. The relative unit blood flow of the APH group was 1/7 times that of the normals in the apex. This normalization by myocardial volume distinguishes cases of APH whose SPECT images resemble the distributions of normal cases.

  12. Frontal subcutaneous blood flow, and epi- and subcutaneous temperatures during scalp cooling in normal man

    DEFF Research Database (Denmark)

    Bülow, J; Friberg, L; Gaardsting, O


    during cooling and rewarming and to measure the effect of scalp cooling on subcutaneous scalp blood flow, subcutaneous blood flow and epi- and subcutaneous temperatures were measured in the frontal region at the hairline border before and during cooling with a cooling helmet, during spontaneous rewarming...

  13. Regional blood flow during exercise in humans measured by near-infrared spectroscopy and indocyanine green

    DEFF Research Database (Denmark)

    Boushel, R; Langberg, Henning; Olesen, J


    Using near-infrared spectroscopy (NIRS) and the tracer indocyanine green (ICG), we quantified blood flow in calf muscle and around the Achilles tendon during plantar flexion (1-9 W). For comparison, blood flow in calf muscle was determined by dye dilution in combination with magnetic resonance...

  14. The significance of noninvasive blood flow studies in the diabetic patient contemplating elective foot surgery. (United States)

    Hill, M; Reinherz, R P; Tisa, L M


    A retrospective study was undertaken to determine the importance of performing noninvasive blood flow studies on the diabetic patient population prior to undergoing elective foot surgery. Thirty diabetic patients, contemplating elective foot surgery, underwent noninvasive blood flow studies. Eighty-seven percent of these patients, with ankle/brachial indices greater than 0.6, successfully healed after surgery was performed.

  15. Renal cortical and medullary blood flow responses to altered NO-availability in humans

    DEFF Research Database (Denmark)

    Damkjaer, Mads; Vafaee, Manoucher; Møller, Michael Lehd


    The objective was to quantify regional renal blood flow in humans. In nine young volunteers on a controlled diet, the lower abdomen was CT-scanned and regional renal blood flow determined by positron emission tomography (PET) scanning using H(2)(15)O as tracer. Measurements were performed at base...

  16. Mucosal/submucosal blood flow in the gut wall determined by local washout of 133Xenon

    DEFF Research Database (Denmark)

    Mortensen, Peter; Olsen, J; Bülow, J


    A 133Xe washout technique for measuring the blood flow in the intestinal mucosa is introduced and evaluated. In 11 anaesthetized pigs a laparotomy was performed and the mucosal blood flow rate in the intestine of the pig was determined by a local epimucosal application of 133Xe. In both the colon...

  17. Contrast sensitivity, ocular blood flow and their potential role in assessing ischaemic retinal disease. (United States)

    Shoshani, Yochai Z; Harris, Alon; Rusia, Deepam; Spaeth, George L; Siesky, Brent; Pollack, Ayala; Wirostko, Barbara


    To examine the definition, evaluation methodology, association to ocular blood flow and potential clinical value of contrast sensitivity (CS) testing in clinical and research settings, focusing in patients with ischemic retinal disease. A review of the medical literature focusing on CS and ocular blood flow in ischemic retinal disease. CS may be more sensitive than other methods at detecting subtle defects or improvements in primarily central retinal ganglion cell function early on in a disease process. CS testing attempts to provide spatial detection differences which are not directly assessed with standard visual acuity chart testing. Analyzing all studies that have assessed both CS change and ocular blood flow, it is apparent that both choroidal circulation and retinal circulation may have an important role in influencing CS. The concept that CS is directly influenced by ocular blood flow is supported by reviewing the studies involving both. Although the studies in the literature have not established a direct cause and effect relationship per se, the literature review makes it logical to assume that changes in retinal and choroidal blood flow influence CS. This raises the possibility that a subjective visual characteristic, specifically CS, may be able to be evaluated more objectively by studying blood flow. It appears appropriate to study the relationship between blood flow and CS more extensively to develop improved ways of measuring various aspects of blood flow to the eye and to best quantify early changes in visual function. © 2011 The Authors. Acta Ophthalmologica © 2011 Acta Ophthalmologica Scandinavica Foundation.

  18. Effects of inspiratory resistance, inhaled beta-agonists and histamine on canine tracheal blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, W.T.; Baile, E.M.; Brancatisano, A.; Pare, P.D.; Engel, L.A. (Dept. of Respiratory Medicine, Westmead Hospital, Westmead, NSW (Australia))


    Tracheobronchial blood flow is potentially important in asthma as it could either influence the clearance of mediators form the airways, thus affecting the duration and severity of bronchoispasm, or enhance oedema formation with a resultant increase in airflow obstruction. In anaesthetized dogs, spontaneously breathing via a tracheostomy, we investigated the effects of three interventions which are relevant to acute asthma attacks and could potentially influence blood flow and its distribution to the mucosa and remaining tissues of the trachea: (1) increased negative intrathoracic pressure swings (-25[+-]1 cmH[sub 2]O) induced by an inspiratory resistance; (2) variable inhaled doses of a beta-adrenoceptor-agonist (terbutaline); and (3) aerosolized histamine sufficient to produce a threefold increase in pulmonary resistance. Microspheres labelled with different radioisotopes were used to measure blood flow. Resistive breathing did not influence tracheobronchial blood flow. Following a large dose of terbutaline, mucosal blood flow (Qmb) increased by 50%. After inhaled histamine, Qmb reached 265% of the baseline value. We conclude that, whereas increased negative pressure swings do not influence tracheobronchial blood flow or its distribution, inhalation of aerosolized terbutaline, corresponding to a conventionally nebulized dose, increases mucosal blood flow. Our results also confirm that inhaled histamine, in a dose sufficient to produce moderate bronchoconstriction, increases tracheal mucosal blood flow in the area of deposition. (au).

  19. Non-gated fetal MRI of umbilical blood flow in an acardiac twin

    Energy Technology Data Exchange (ETDEWEB)

    Hata, Nobuhiko [University of Tokyo, Graduate School of Information Science and Technology, Tokyo (Japan); Brigham and Women' s Hospital, Department of Radiology, Boston, MA (United States); Wada, Toru [University of Tokyo, Graduate School of Information Science and Technology, Tokyo (Japan); Kashima, Kyoko; Okada, Yoshiyuki [National Center for Child Health and Development, Department of Radiology, Tokyo (Japan); Unno, Nobuya [Nagano Children' s Hospital, Center for Perinatal Medicine, Nagano (Japan); Kitagawa, Michihiro [National Center for Child Health and Development, Department of Prenatal Medicine and Maternal Care, Tokyo (Japan); Chiba, Toshio [National Center for Child Health and Development, Department of Strategic Medicine, Tokyo (Japan)


    Currently, the standard method of diagnosis of twin reversed arterial perfusion (TRAP) sequence is ultrasound imaging. The use of MRI for flow visualization may be a useful adjunct to US imaging for assessing the presence of retrograde blood flow in the acardiac fetus and/or umbilical artery. The technical challenge in fetal MRI flow imaging, however, is that fetal electrocardiogram (ECG) monitoring required for flow imaging is currently unavailable in the MRI scanner. A non-gated MRI flow imaging technique that requires no ECG monitoring was developed using the t-test to detect blood flow in 20 slices of phase-contrast MRI images randomly scanned at the same location over multiple cardiac cycles. A feasibility study was performed in a 24-week acardiac twin that showed no umbilical flow sonographically. Non-gated MRI flow images clearly indicated the presence of blood flow in the umbilical artery to the acardiac twin; however, there was no blood flow beyond the abdomen. This study leads us to conjecture that non-gated MRI flow imaging is sensitive in detecting low-range blood flow velocity and can be an adjunct to Doppler US imaging. (orig.)

  20. [Changes of blood flow volume in dog's mental artery after mandible osteocompression]. (United States)

    Huang, Xiao-Feng; Zeng, Xiang-Long


    To observe the changes of blood flow volume in mental artery of dog before and after osteocompression. 16 adult dogs were selected and the osteocompressors were fixed on the right buccal side of the mandible. The osteocompressor was used to compress the mandible 1.0 mm per 3 days for totally 15 days. On the 1st, 15th, 45th and 90th day after osteocompression, the 4 MHz prober of color Doppler flow imaging machine was put on the surface of the mucosa below which there was the mental artery. The color Doppler flow imaging was used to measure the blood flow volume in the mental artery of both experimental and control sides. 1) The blood flow value in the mental artery was the lowest on the 15th day after osteocompression, however there was not significantly different before and after osteocompression. 2) Compared with the control, the blood flow value of the mental artery on the 1st day after experiment was significantly decreased. 3) Compared with the data before experiment, the deduction of the blood flow values between experimental side and control on the 1st, 15th and 45th day after osteocompression had significant differences. On the 90th day, the deduction of the blood flow value was similar to normal. The osteocompression influences blood flow volume in mental artery temporarily, however, the influence is reversible and can be recovered by times after osteocompression.

  1. Passive restriction of blood flow and counter-current heat exchange via lingual retia in the tongue of a neonatal gray whale Eschrichtius robustus (Cetacea, Mysticeti). (United States)

    Ekdale, Eric G; Kienle, Sarah S


    Retia mirabilia play broad roles in cetacean physiology, including thermoregulation during feeding and pressure regulations during diving. Vascular bundles of lingual retia are described within the base of the tongue of a neonatal female gray whale (Eschrichtius robustus). Each rete consists of a central artery surrounded by four to six smaller veins. The retia and constituent vessels decrease in diameter as they extend anteriorly within the hyoglossus muscle from a position anterior to the basihyal cartilage toward the apex of the tongue. The position of the retia embedded in the hyoglossus and the anterior constriction of the vessels differs from reports of similar vascular bundles that were previously identified in gray whales. The retia likely serve as a counter-current heat exchange system to control body temperature during feeding. Cold blood flowing toward the body center within the periarterial veins would accept heat from warm blood in the central artery flowing toward the anterior end of the tongue. Although thermoregulatory systems have been identified within the mouths of a few mysticete species, the distribution of such vascular structures likely is more widespread among baleen whales than has previously been described. © 2015 Wiley Periodicals, Inc.

  2. Magnetic field effect on blood flow of Casson fluid in axisymmetric cylindrical tube: A fractional model

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Farhad, E-mail: [Department of Mathematics, City University of Science and Information Technology, Peshawar 25000 (Pakistan); Sheikh, Nadeem Ahmad [Department of Mathematics, City University of Science and Information Technology, Peshawar 25000 (Pakistan); Khan, Ilyas [Basic Engineering Sciences Department, College of Engineering Majmaah University, Majmaah 11952 (Saudi Arabia); Saqib, Muhammad [Department of Mathematics, City University of Science and Information Technology, Peshawar 25000 (Pakistan)


    The effects of magnetohydrodynamics on the blood flow when blood is represented as a Casson fluid, along with magnetic particles in a horizontal cylinder is studied. The flow is due to an oscillating pressure gradient. The Laplace and finite Hankel transforms are used to obtain the closed form solutions of the fractional partial differential equations. Effects of various parameters on the flow of both blood and magnetic particles are shown graphically. The analysis shows that, the model with fractional order derivatives bring a remarkable changes as compared to the ordinary model. The study highlights that applied magnetic field reduces the velocities of both the blood and magnetic particles.

  3. A New Method to Measure Portal Venous and Hepatic Arterial Blood Flow Patients Intraoperatively (United States)

    Jakab, F.; Ráth, Z.; Schmal, F.; Nagy, P.; Faller, J.


    The intraoperative measurement of the afferent circulation of the liver, namely the hepatic artery flow and portal venous flow was carried out upon 14 anesthetized patients having carcinoma in the splanchnic area, mainly in the head of the pancreas by means of transit time ultrasonic volume flowmeter. The hepatic artery flow, portal venous flow and total hepatic flow were 0.377±0.10; 0.614±0.21; 0.992±0.276 l/min respectively. The ratio of hepatic arterical flow to portal venous flow was 0.66±0.259 There was a sharp, significant increase in hepatic arterial flow (29.8±6.1%, p<0,01) after the temporary occlusion of the portal vein, while the temporary occlusion of hepatic artery did not have any significant effect on portal venous circulation. The interaction between hepatic arterial flow and portal venous flow is a much disputed question, but according to the presented data here, it is unquestionable, that the decrease of portal venous flow immediately results a significant increase in hepatic artery circulation. PMID:8809586

  4. A disturbed macrocirculatory supply as a determinant for a reduced sciatic nerve blood flow in diabetic rats

    NARCIS (Netherlands)

    Gispen, W.H.; Buren, Th. van; Kappelle, A.C.; Kasbergen, C.M.; Wildt, D.J. de


    The aim of this study was to evaluate macrocirculatory disturbances in relation to the reduced sciatic nerve blood flow seen in diabetic rats. Therefore, both femoral blood flow, the macrocirculatory arterial blood supply to the sciatic nerve, and the microcirculatory neuronal blood flow were

  5. Basic taste stimuli elicit unique responses in facial skin blood flow.

    Directory of Open Access Journals (Sweden)

    Hideaki Kashima

    Full Text Available Facial expression changes characteristically with the emotions induced by basic tastes in humans. We tested the hypothesis that the five basic tastes also elicit unique responses in facial skin blood flow. Facial skin blood flow was measured using laser speckle flowgraphy in 16 healthy subjects before and during the application of basic taste stimuli in the oral cavity for 20 s. The skin blood flow in the eyelid increased in response to sweet and umami taste stimuli, while that in the nose decreased in response to a bitter stimulus. There was a significant correlation between the subjective hedonic scores accompanying these taste stimuli and the above changes in skin blood flow. These results demonstrate that sweet, umami, and bitter tastes induce unique changes in facial skin blood flow that reflect subjective hedonic scores.

  6. Effects of neuropeptide Y on regulation of blood flow rate in canine myocardium

    DEFF Research Database (Denmark)

    Svendsen, Jesper Hastrup; Sheikh, S P; Jørgensen, J


    The effect of neuropeptide Y (NPY) on tension development was examined in isolated canine coronary arteries, and the effects on local myocardial blood flow rate were studied in open-chest anesthetized dogs by the local 133Xe washout technique. By immunohistochemistry, numerous NPY......+. In contrast, intracoronary NPY (0.01-10 micrograms) induced a considerable degree of vasoconstriction; the reduction of blood flow rate was dose related, with a maximum reduction to 52% of control values. The effect of intracoronary NPY (1 microgram) on maximally relaxed arterioles elicited by 30 s...... of ischemia was studied in separate experiments during reactive hyperemia. NPY induced a decrease in maximum blood flow during reactive hyperemia (166.6 vs. 214.6% of preocclusive blood flow rate, mean values; P = 0.05), an increase in the cumulative excess blood flow (61.0 vs. 35.3 ml/100 g; P = 0...

  7. Outcome of splanchnic blood flow determination in patients with suspected chronic intestinal ischaemia. A retrospective survey

    DEFF Research Database (Denmark)

    Møller, Søren; Madsen, Jan Lysgård


    BACKGROUND: Different diagnostic examinations have been applied in the management of patients with suspected intestinal ischaemia. In some centres, invasive determination of a meal-induced increase in splanchnic blood flow is used in the diagnostic process and in the selection of patients for sur...... underwent angioplasty. Future studies are needed to validate the determination of splanchnic blood flow in relation to splanchnic angiography and other imaging modalities in patients with chronic intestinal ischaemia.......BACKGROUND: Different diagnostic examinations have been applied in the management of patients with suspected intestinal ischaemia. In some centres, invasive determination of a meal-induced increase in splanchnic blood flow is used in the diagnostic process and in the selection of patients...... for surgery. However, no studies have evaluated the impact of splanchnic blood flow determination on therapy in such patients. OBJECTIVE: The aim of the present study was therefore to analyse the outcome of splanchnic blood flow determination in patients with suspected chronic intestinal ischaemia. METHODS...

  8. Loss of autoregulation of blood flow in subcutaneous tissue in juvenile diabetes

    DEFF Research Database (Denmark)

    Henriksen, O; Kastrup, J; Parving, H H


    The autoregulation of blood flow in subcutaneous tissue was investigated at the level of the lateral malleolus by the local 133Xenon washout technique. We have investigated eight long-term insulin-dependent diabetics and seven healthy controls. All diabetics had moderate diabetic nephropathy...... and retinopathy. The blood flow remained constant in all normal subjects, when the arterial perfusion pressure was varied between 70 and 150 mm Hg. All diabetics had impaired or reduced autoregulation of the subcutaneous blood flow. The blood flow increased and decreased almost linearly with the changes...... in arterial perfusion pressure. The mechanism underlying the defect autoregulation of blood flow in diabetics is uncertain; possibilities include structural changes of the arterioles and/or alterations of local metabolic factors....

  9. Micro-PIV quantification of capillary blood flow redistribution caused by laser-assisted vascular occlusion (United States)

    Kurochkin, Maxim A.; Stiukhina, Elena S.; Fedosov, Ivan V.; Postnov, Dmitry E.; Tuchin, Valery V.


    We propose μPIV-based technique for quantitative assessment of blood flow redistribution in microcirculatory networks. Our approach is based on per-segment averaging of measured quantities so we can avoid most of problems that are typical for point-wise measurements. The key point of our technique is the digital processing algorithms of recorded data that include: capillary network axial line construction; interrogation regions centering; blood flow velocity local estimate using PIV approach; blood flow velocity calculation by means of averaging over entire vessel segment; the calculation of blood volume flow rate map. We illustrate the application of developed technique with in vivo measurements and blood flow velocity map reconstruction for chorioallantoic membrane (CAM) of chicken embryo, in which the local vascular occlusion was produced using continuous wave laser light irradiation..

  10. Influence of cold-water immersion on limb blood flow after resistance exercise. (United States)

    Mawhinney, Chris; Jones, Helen; Low, David A; Green, Daniel J; Howatson, Glyn; Gregson, Warren


    This study determined the influence of cold (8°C) and cool (22°C) water immersion on lower limb and cutaneous blood flow following resistance exercise. Twelve males completed 4 sets of 10-repetition maximum squat exercise and were then immersed, semi-reclined, into 8°C or 22°C water for 10-min, or rested in a seated position (control) in a randomized order on different days. Rectal and thigh skin temperature, muscle temperature, thigh and calf skin blood flow and superficial femoral artery blood flow were measured before and after immersion. Indices of vascular conductance were calculated (flux and blood flow/mean arterial pressure). The colder water reduced thigh skin temperature and deep muscle temperature to the greatest extent (P cold and cool water similarly reduce femoral artery and cutaneous blood flow responses but not muscle temperature following resistance exercise.

  11. Decreased cerebral blood flow after administration of sodium bicarbonate in the distressed newborn infant

    DEFF Research Database (Denmark)

    Lou, H C; Lassen, N A; Fris-Hansen, B


    In the course of our studies on cerebral blood flow in newborn infants, we have observed a striking depressing effect of sodium bicarbonate infusion on cerebral blood flow which in some cases may severely aggravate cerebral ischemia. We measured cerebral blood flow before and after the treatment...... with 1 to 8 meqs of sodium bicarbonate in seven distressed newborn infants. The 133 Xe clearance technique was used. The results showed in six of the seven cases a decrease in cerebral blood flow, which in most cases was reduced to 14 to 22 ml/100 g/min, which is about half the value prior...... to the bicarbonate infusion. In one case an extreme reduction occurred: cerebral blood flow was reduced to 3 ml/100 g/min, well below the level compatible with tissue survival. The results are discussed with regard to the optimal treatment of the acidotic newborn....

  12. Effect of spinal sympathetic blockade upon postural changes of blood flow in human peripheral tissues

    DEFF Research Database (Denmark)

    Skagen, K; Haxholdt, O; Henriksen, O


    in subcutaneous tissue and skeletal muscle to head-up tilt whereas local blockade was able to prevent the response. Local mechanisms including the local veno-arteriolar reflex appear to play an important role for the observed maintenance of arterial blood pressure in the tilted position during central sympathetic......The effect of head-up tilt upon subcutaneous and skeletal muscle blood flow in the crus was studied before and during epidural blockade in 10 subjects. Relative changes in blood flow were estimated by the local 133Xe washout technique. In subcutaneous tissue head-up tilt induced a decrease in blood...... local nervous blockade was induced by Lidocaine in 133Xe labelled subcutaneous tissue on one side. During epidural blockade and tilt blood flow increased by 12% whereas blood flow decreased by 30% on the control side. Thus epidural blockade had no influence on the vasoconstrictor response...

  13. Blood flow velocity imaging of malignant melanoma by micro multipoint laser Doppler velocimetry (United States)

    Ishida, H.; Andoh, T.; Akiguchi, S.; Shirakawa, H.; Kobayashi, D.; Kuraishi, Y.; Hachiga, T.


    We have developed a laser Doppler velocimeter to measure blood flow, the micromultipoint laser Doppler velocimeter (μ-MLDV). This equipment can measure absolute velocity and, based on this, can display the course of blood vessels. In this study, we attempted to perform blood flow velocity imaging of malignant melanoma transplanted to the mouse ear. We found that blood flow velocity of the formed blood vessels originating in the melanoma was much greater than that of the capillary vessels in normal skin. Furthermore, the form of the tumor was clearly visible from the blood flow velocity image. These experimental results suggest that μ-MLDV has potential as a diagnostic method for distinguishing benign nevi from malignant melanomas.

  14. Dynamics of uranium vein mineralization

    Energy Technology Data Exchange (ETDEWEB)

    Petrosyan, R.V. (Ministerstvo Geologii SSR, Moscow)


    The formation of uraniun vein deposits and the essence of consanguinity of the mineralization and wall metasomatites are considered. The formation of uranium mineralization is analysed from the positions of Korzhinsky D. S. : the formation of metasomatite aureole and associated vein ores take place as a result of the development of one solution flow while the formation of mineral vein associations occurs on the background of continuous filtration of the solution during metasomato is due to a repeated (pulse) half-opening of fractures and their filling with a part of filtrating solution. The analysis of the available information on the example of two different uranium manifestations permits to reveal certain relations both in the character of wall rock alterations and between the metasomatosis and the formation of ore minerals in veins. The conclusion is made that spatial-time correlations of vein formations with wall metasomatites attest that the pulse formation of ores in veinlets occurs on the background and in interrelation with a consecutive precipitation of components in the aureole volume. The analysis of element migration dynamics in wall aureole carried out from the positions of the Korzhinsky hypothesis of the advance wave of acid components that takes into account the interaction of continuous and pulse mechanisms of solution movement permits to avoid contradictions when interpreting the processes of wall rock alterations and vein ore-forming, and permits to make a common scheme of vein ore-genesis.

  15. [Treatment of venous trophic ulcers, using echoscleroobliteration of perforant veins]. (United States)

    Rusyn, V I; Korsak, V V; Boldizhar, P O; Borsenko, M I; Mytrovka, B A


    In 36 patients, suffering trophic ulcers on a chronic venous insufficiency background in a decompensated stage (C6 in accordance to CEAP), echoscleroobliteration of perforant veins, using a "foam-form" method in accordance to Tessari, was performed. In 29 patients postrombophlebitic syndrome in incomplete recanalization stage was diagnosed, in 7 recurrence of varicose disease of the lower extremities. In all the patients during echoscleroobliteration there was possible to obliterate the insufficient perforant veins, in 3 patients two perforant veins were obliterated in each of them. In a one week a pathological blood flow along perforant veins, in accordance to data of ultrasound duplex scanning, was absent. This effect lasted during 6 mo in 29 (80.6%) patients. In 25 (69.4%) patients a trophic ulcers healing was achieved in 1 - 3 mo. In a one year in 30 (83.3%) patients a stable obliteration was noted, in 3 (8.3%) - partial recanalization, in 3 (8.3%) - complete recanalization of perforant veins.

  16. Augmenting regional cerebral blood flow using external-to-internal carotid artery flow diversion method. (United States)

    Divani, Afshin A; Berezina, Tamara L; Vazquez, Gabriela; Zaets, Sergey B; Tummala, Ramachandra; Qureshi, Adnan I


    The objective of this study was to assess the effect of flow diversion by external carotid artery (ECA) occlusion on ipsilateral regional cerebral blood flow (rCBF). Local cerebral hyperperfusion in rats (n = 12) was induced by ligating the right ECA. Ipsilateral rCBF was determined pre- and post-ligation for 120 min using a laser Doppler flow meter. Sham animals (n = 6) were subjected to the craniotomy without ligation of the right ECA. In a separate series of rats (n = 5), brain tissue oxygen levels (pO(2)) in the right and left brain hemispheres were determined before and 90 min after ligation of the right ECA using a tissue oxygenation monitoring unit. We investigated the effect of ECA occlusion hemispheric changes in rCBF in one clinical case as a proof of concept. Ligation of ECA resulted in a statistically significant increase in rCBF on the ipsilateral side compared to the sham-operated rats (p group compared with sham-operated rats. There was no significant variation in MAP for the treated animals. Vascular permeability and cerebral water content in the right hemisphere after ligation of ECA did not significantly differ from the contralateral hemisphere. Ipsilateral hemisphere tissue pO(2) was significantly higher compared to the contralateral area (p ECA resulted in 3.6% and 12.1% increase in peak value and rise-time of the time-density curves. Flow diversion by temporary occlusion of the ECA can result in increased rCBF and cerebral pO(2) on the ipsilateral side. The strategy may represent a viable option to augment rCBF in focal cerebral ischemia.

  17. Brain blood-flow changes during motion sickness. [thalamus vascular changes in dogs during swing tests (United States)

    Johnson, W. H.; Hsuen, J.


    The possibility of diminished blood flow in the brain is studied as one of the factors resulting from an increase in skeletal muscle blood volume concomitant with other characteristics of motion sickness. Thermistors are implanted in the thalamus of dogs and blood flow changes are recorded while they are subjected to sinusoidal movement on a two pole swing. Results of these initial steps in a proposed long term exploration of different areas of the brain are presented.

  18. Usage of CO2 microbubbles as flow-tracing contrast media in X-ray dynamic imaging of blood flows. (United States)

    Lee, Sang Joon; Park, Han Wook; Jung, Sung Yong


    X-ray imaging techniques have been employed to visualize various biofluid flow phenomena in a non-destructive manner. X-ray particle image velocimetry (PIV) was developed to measure velocity fields of blood flows to obtain hemodynamic information. A time-resolved X-ray PIV technique that is capable of measuring the velocity fields of blood flows under real physiological conditions was recently developed. However, technical limitations still remained in the measurement of blood flows with high image contrast and sufficient biocapability. In this study, CO2 microbubbles as flow-tracing contrast media for X-ray PIV measurements of biofluid flows was developed. Human serum albumin and CO2 gas were mechanically agitated to fabricate CO2 microbubbles. The optimal fabricating conditions of CO2 microbubbles were found by comparing the size and amount of microbubbles fabricated under various operating conditions. The average size and quantity of CO2 microbubbles were measured by using a synchrotron X-ray imaging technique with a high spatial resolution. The quantity and size of the fabricated microbubbles decrease with increasing speed and operation time of the mechanical agitation. The feasibility of CO2 microbubbles as a flow-tracing contrast media was checked for a 40% hematocrit blood flow. Particle images of the blood flow were consecutively captured by the time-resolved X-ray PIV system to obtain velocity field information of the flow. The experimental results were compared with a theoretically amassed velocity profile. Results show that the CO2 microbubbles can be used as effective flow-tracing contrast media in X-ray PIV experiments.

  19. Regional cerebral blood flow abnormalities in patients with primary hyperparathyroidism

    Energy Technology Data Exchange (ETDEWEB)

    Cermik, Tevfik F. [Hospital of the University of Trakya, Department of Nuclear Medicine, Edirne (Turkey); Trakya Universitesi Hastanesi, Nukleer Tip Anabilim Dali, Gullapoglu Yerleskesi, Edirne (Turkey); Kaya, Meryem; Bedel, Deniz; Berkarda, Sakir; Yigitbasi, Oemer N. [Hospital of the University of Trakya, Department of Nuclear Medicine, Edirne (Turkey); Ugur-Altun, Betuel [Hospital of the University of Trakya, Department of Internal Medicine, Division of Endocrinology, Edirne (Turkey)


    We assessed the alterations in regional cerebral blood flow (rCBF) in patients with primary hyperparathyroidism (PHP) before parathyroidectomy by semiquantitative analysis of brain single photon emission computed tomography (SPECT) images. Included in this prospective study were 14 patients (mean age 47.6 {+-} 10.4 years; 3 male, 11 female) and 10 control subjects (mean age 36.0 {+-} 8.5 years, 6 male, 4 female) were SPECT imaging was performed using a dual-headed gamma camera 60-90 min after intravenous administration of 925 MBq Tc-99m HMPAO. The corticocerebellar rCBF ratios were calculated from 52 brain areas and reference lower values (RLVs) were calculated from the rCBF ratios of control subjects. The regional ratios that were below the corresponding RLV were considered abnormal (hypoperfused). Hypoperfusion was shown in 171 out of 728 regions (23%) and there was a significant correlation between serum calcium, PTH levels and the sum of hypoperfused regions in the patient group (R = 0.75 and P = 0.001, and R = 0.75, P = 0.001, respectively). Significantly reduced rCBF were found in the following cortical regions: bilateral cingulate cortex, superior and inferior frontal cortex, anterior temporal cortex, precentral gyrus, postcentral gyrus and parietal cortex, and right posterior temporal cortex. Our results indicate that alterations in rCBF in patients with PHP can be demonstrated with brain SPECT. The correlation between serum calcium, PTH levels and the sum of hypoperfused regions indicates that there may be a strong relationship between rCBF abnormalities and increased levels of serum calcium and PTH. In addition, the degree of rCBF abnormalities could be determined by brain SPECT in PHP patients with or without psychiatric symptoms. (orig.)

  20. Skin Blood Flow and Vascular Endothelium Function in Uremia. (United States)

    Smogorzewski, Miroslaw J


    Prevalence of dermatological disorder in patients with end-stage kidney disease is estimated as 50% to 100% in various studies. Some of the skin lesions are specific for the diseases causing chronic kidney disease (CKD), some are associated with CKD, and still others are the dermatological manifestation of uremia. Microangiopathy was also found in both arterioles and venule in the skin biopsy of "normal looking" skin in patients with end-stage kidney disease. In a cross-sectional study in patients on dialysis, we measured skin blood flow (SBF) using laser Doppler device in a standardized way at various areas of lower extremities at 2 different local skin temperatures: 35°C and 44°C. Local heating increases skin perfusion by mechanisms dependent on nitric oxide (NO). SBF was impaired in CKD patients Stage 5 on HD, particularly in those with diabetes mellitus as a cause of CKD. The reduced response in the SBF to the heat in our patients may be due to decreased generation of NO in uremia. Endothelium-dependent vasodilatation in patients on dialysis and the response of the skin microcirculation to acetylcholine was diminished in hypertensive patients on dialysis. Similarly, patients with diabetes mellitus had decreased SBF during intradermal microdialysis with a NO synthase inhibitor. Multiple uremic toxins have been studied in vitro and show to cause various degree of endothelial cell dysfunction. Unfortunately, no clear benefit has been described in CKD patients to different intervention aimed to reduce uremic toxin effect on endothelium. There are no long-term data on the factors which can modify endothelium function in uremia, but non pharmacologic interventions, diet, and several pharmacologic approaches could be beneficial. Measurement of SBF can be useful in evaluation of vasculopathy in CKD population and can potentially be used for assessment of vascular response during specific clinical intervention. Copyright © 2017. Published by Elsevier Inc.

  1. Hypoxemia, oxygen content, and the regulation of cerebral blood flow (United States)

    Bain, Anthony R.; Rieger, Mathew G.; Bailey, Damian M; Ainslie, Philip N.


    This review highlights the influence of oxygen (O2) availability on cerebral blood flow (CBF). Evidence for reductions in O2 content (CaO2) rather than arterial O2 tension (PaO2) as the chief regulator of cerebral vasodilation, with deoxyhemoglobin as the primary O2 sensor and upstream response effector, is discussed. We review in vitro and in vivo data to summarize the molecular mechanisms underpinning CBF responses during changes in CaO2. We surmise that 1) during hypoxemic hypoxia in healthy humans (e.g., conditions of acute and chronic exposure to normobaric and hypobaric hypoxia), elevations in CBF compensate for reductions in CaO2 and thus maintain cerebral O2 delivery; 2) evidence from studies implementing iso- and hypervolumic hemodilution, anemia, and polycythemia indicate that CaO2 has an independent influence on CBF; however, the increase in CBF does not fully compensate for the lower CaO2 during hemodilution, and delivery is reduced; and 3) the mechanisms underpinning CBF regulation during changes in O2 content are multifactorial, involving deoxyhemoglobin-mediated release of nitric oxide metabolites and ATP, deoxyhemoglobin nitrite reductase activity, and the downstream interplay of several vasoactive factors including adenosine and epoxyeicosatrienoic acids. The emerging picture supports the role of deoxyhemoglobin (associated with changes in CaO2) as the primary biological regulator of CBF. The mechanisms for vasodilation therefore appear more robust during hypoxemic hypoxia than during changes in CaO2 via hemodilution. Clinical implications (e.g., disorders associated with anemia and polycythemia) and future study directions are considered. PMID:26676248

  2. Carbon dioxide induced changes in cerebral blood flow and flow velocity: Role of cerebrovascular resistance and effective cerebral perfusion pressure

    NARCIS (Netherlands)

    F. Grüne (Frank); S. Kazmaier (Stephan); R.J. Stolker (Robert J.); G.H. Visser (Gerhard Henk); A. Weyland (Andreas)


    textabstractIn addition to cerebrovascular resistance (CVR) zero flow pressure (ZFP), effective cerebral perfusion pressure (CPPe) and the resistance area product (RAP) are supplemental determinants of cerebral blood flow (CBF). Until now, the interrelationship of PaCO2 -induced changes in CBF, CVR,

  3. Blood flow measurements during hemodialysis vascular access interventions - Catheter-based thermodilution or Doppler ultrasound?

    DEFF Research Database (Denmark)

    Heerwagen, Søren T; Hansen, Marc A; Schroeder, Torben V


    Purpose: To test the clinical performance of catheter-based thermodilution and Doppler ultrasound of the feeding brachial artery for blood flow measurements during hemodialysis vascular access interventions.Methods: Thirty patients with arteriovenous fistulas who underwent 46 interventions had...... access blood flow measured before and after every procedure. Two methods, catheter-based thermodilution and Doppler ultrasound, were compared to the reference method of ultrasound dilution. Catheter-based thermodilution and Doppler ultrasound were performed during the endovascular procedures while flow...

  4. Regional cerebral blood flow in stroke by 133Xenon inhalation and emission tomography

    DEFF Research Database (Denmark)

    Lassen, N A; Henriksen, L; Paulson, O


    A rapidly rotating single-photon emission tomograph was used to study regional cerebral blood flow by 133Xenon inhalation. Using a rotation speed of 180 degrees/5 sec a tomographic picture of the average Xenon concentration in 3 slices is obtained. By taking a sequence of 4 one-minute tomograms...... cerebral blood flow measured tomographically by 133Xenon inhalation circumvents the extra-cranial contamination and the superposition of intracranial tissues that hamper 133Xenon inhalation flow studies using stationary detectors....

  5. Computational Fluid Dynamics Analysis of Pulsatile Blood Flow Behavior in Modelled Stenosed Vessels with Different Severities

    Directory of Open Access Journals (Sweden)

    Mohsen Mehrabi


    Full Text Available This study focuses on the behavior of blood flow in the stenosed vessels. Blood is modelled as an incompressible non-Newtonian fluid which is based on the power law viscosity model. A numerical technique based on the finite difference method is developed to simulate the blood flow taking into account the transient periodic behaviour of the blood flow in cardiac cycles. Also, pulsatile blood flow in the stenosed vessel is based on the Womersley model, and fluid flow in the lumen region is governed by the continuity equation and the Navier-Stokes equations. In this study, the stenosis shape is cosine by using Tu and Devil model. Comparing the results obtained from three stenosed vessels with 30%, 50%, and 75% area severity, we find that higher percent-area severity of stenosis leads to higher extrapressure jumps and higher blood speeds around the stenosis site. Also, we observe that the size of the stenosis in stenosed vessels does influence the blood flow. A little change on the cross-sectional value makes vast change on the blood flow rate. This simulation helps the people working in the field of physiological fluid dynamics as well as the medical practitioners.

  6. Longitudinal optical monitoring of blood flow in breast tumors during neoadjuvant chemotherapy (United States)

    Cochran, J. M.; Chung, S. H.; Leproux, A.; Baker, W. B.; Busch, D. R.; DeMichele, A. M.; Tchou, J.; Tromberg, B. J.; Yodh, A. G.


    We measure tissue blood flow markers in breast tumors during neoadjuvant chemotherapy and investigate their correlation to pathologic complete response in a pilot longitudinal patient study (n  =  4). Tumor blood flow is quantified optically by diffuse correlation spectroscopy (DCS), and tissue optical properties, blood oxygen saturation, and total hemoglobin concentration are derived from concurrent diffuse optical spectroscopic imaging (DOSI). The study represents the first longitudinal DCS measurement of neoadjuvant chemotherapy in humans over the entire course of treatment; it therefore offers a first correlation between DCS flow indices and pathologic complete response. The use of absolute optical properties measured by DOSI facilitates significant improvement of DCS blood flow calculation, which typically assumes optical properties based on literature values. Additionally, the combination of the DCS blood flow index and the tissue oxygen saturation from DOSI permits investigation of tissue oxygen metabolism. Pilot results from four patients suggest that lower blood flow in the lesion-bearing breast is correlated with pathologic complete response. Both absolute lesion blood flow and lesion flow relative to the contralateral breast exhibit potential for characterization of pathological response. This initial demonstration of the combined optical approach for chemotherapy monitoring provides incentive for more comprehensive studies in the future and can help power those investigations.

  7. A Vein Map Biometric System

    Directory of Open Access Journals (Sweden)

    Felix Fuentes


    Full Text Available There is increasing demand world-wide, from government agencies and the private sector for cutting-edge biometric security technology that is difficult to breach but userfriendly at the same time. Some of the older tools, such as fingerprint, retina and iris scanning, and facial recognition software have all been found to have flaws and often viewed negatively because of many cultural and hygienic issues associated with them. Comparatively, mapping veins as a human barcode, a new technology, has many advantages over older technologies. Specifically, reproducing a three-dimensional model of a human vein system is impossible to replicate. Vein map technology is distinctive because of its state-of-the-art sensors are only able to recognize vein patterns if hemoglobin is actively flowing through the person

  8. Multi-modal in vivo imaging of brain blood oxygenation, blood flow and neural calcium dynamics during acute seizures (United States)

    Ringuette, Dene; Jeffrey, Melanie A.; Carlen, Peter L.; Levi, Ofer


    Dysfunction of the vascular endothelium has been implicated in the development of epilepsy. To better understand the relation between vascular function and seizure and provide a foundation for interpreting results from functional imaging in chronic disease models, we investigate the relationship between intracellular calcium dynamics and local cerebral blood flow and blood oxygen saturation during acute seizure-like events and pharmacological seizure rescue. To probe the relation between the aforementioned physiological markers in an acute model of epilepsy in rats, we integrated three different optical modalities together with electrophysiological recordings: Laser speckle contrast imaging (LSCI) was used to study changes in flow speeds, Intrinsic optical signal imaging (IOSI) was used to monitor changes in oxygenated, de-oxygenated, and total hemoglobin concentration, and Calcium-sensitive dye imaging was used to monitor intracellular calcium dynamics. We designed a dedicated cortical flow chamber to remove superficial blood and dye resulting from the injection procedure, which reduced spurious artifacts. The near infrared light used for IOSI and LSCI was delivered via a light pipe integrated with the flow chamber to minimize the effect of fluid surface movement on illumination stability. Calcium-sensitive dye was injected via a glass electrode used for recording the local field potential. Our system allowed us to observe and correlate increases in intracellular calcium, blood flow and blood volume during seizure-like events and provide a quantitative analysis of neurovascular coupling changes associated with seizure rescue via injection of an anti-convulsive agent.

  9. Forearm blood flow responses of offspring of hypertensives to an extended stress task. (United States)

    Ditto, B; Miller, S B


    The forearm blood flow and other cardiovascular responses of 10 healthy young men with a parental history of hypertension to an extended laboratory stressor were compared with the responses of 10 age-matched men with normotensive parents. To eliminate the effects of the anticipation of stress on baseline measures, all subjects participated in a separate 1-hour counterbalanced baseline session in which no stress was presented. There were no significant differences between the two groups in resting blood pressure, heart rate, blood volume pulse, forearm blood flow and vascular resistance, and self-report anxiety, although offspring of hypertensive parents exhibited marginally greater (p = 0.08) forearm blood flow at rest. During the stress session, subjects played video games for 1 hour and avoided mild electric shocks depending on performance. Offspring of hypertensive parents exhibited significantly greater heart rate (+19 +/- 6 vs. +3 +/- 2%), forearm blood flow (+52 +/- 14 vs. +9 +/- 4%), and self-report anxiety (+25 +/- 6 vs. +9 +/- 3%) responses to the task. There were no significant group differences in blood pressure response to the task. Significant positive correlations between forearm blood flow and heart rate responses to the task were observed. These findings extend earlier results that suggested healthy young offspring of hypertensive and normotensive parents may exhibit different patterns of hemodynamic response to stress in the absence of differences in resting blood pressure or blood pressure responsiveness to stress.

  10. Effect of Rolling Massage on the Vortex Flow in Blood Vessels with Lattice Boltzmann Simulation (United States)

    Yi, Hou Hui

    The rolling massage manipulation is a classic Chinese Medical Massage, which is a nature therapy in eliminating many diseases. Here, the effect of the rolling massage on the cavity flows in blood vessel under the rolling manipulation is studied by the lattice Boltzmann simulation. The simulation results show that the vortex flows are fully disturbed by the rolling massage. The flow behavior depends on the rolling velocity and the rolling depth. Rolling massage has a better effect on the flows in the cavity than that of the flows in a planar blood vessel. The result is helpful to understand the mechanism of the massage and develop the rolling techniques.

  11. Liver blood flow measurement in the rat. The electromagnetic versus the microsphere and the clearance methods

    NARCIS (Netherlands)

    Daemen, M. J.; Thijssen, H. H.; van Essen, H.; Vervoort-Peters, H. T.; Prinzen, F. W.; Struyker Boudier, H. A.; Smits, J. F.


    This study describes the simultaneous measurement of hepatic arterial and portal venous blood flow in the pentobarbital anesthetized rat by means of electromagnetic flowmeters. Hepatic arterial flow was 0.21 +/- 0.02 mL/min/g liver, and portal venous flow was 1.53 +/- 0.19 mL/min/g liver (n = 20).

  12. Renal blood flow, early distal sodium, and plasma renin concentrations during osmotic diuresis

    DEFF Research Database (Denmark)

    Leyssac, P P; Holstein-Rathlou, N H; Skøtt, O


    .6 mmHg. Urine flow increased 10-fold, and sodium excretion increased by 177%. Plasma renin concentration (PRC) increased by 58%. Renal blood flow and glomerular filtration rate decreased, however end-proximal flow remained unchanged. After a similar volume of hypotonic glucose (152 mM), ED...

  13. Influence of exercise intensity on skeletal muscle blood flow, O2 extraction and O2 uptake on-kinetics (United States)

    Jones, Andrew M; Krustrup, Peter; Wilkerson, Daryl P; Berger, Nicolas J; Calbet, José A; Bangsbo, Jens


    Following the start of low-intensity exercise in healthy humans, it has been established that the kinetics of skeletal muscle O2 delivery is faster than, and does not limit, the kinetics of muscle O2 uptake (). Direct data are lacking, however, on the question of whether O2 delivery might limit kinetics during high-intensity exercise. Using multiple exercise transitions to enhance confidence in parameter estimation, we therefore investigated the kinetics of, and inter-relationships between, muscle blood flow (), a– difference and following the onset of low-intensity (LI) and high-intensity (HI) exercise. Seven healthy males completed four 6 min bouts of LI and four 6 min bouts of HI single-legged knee-extension exercise. Blood was frequently drawn from the femoral artery and vein during exercise and , a– difference and were calculated and subsequently modelled using non-linear regression techniques. For LI, the fundamental component mean response time (MRTp) for kinetics was significantly shorter than kinetics (mean ± SEM, 18 ± 4 vs. 30 ± 4 s; P kinetics following the onset of LI or HI knee-extension exercise. PMID:22711961

  14. New optical sensing technique of tissue viability and blood flow based on nanophotonic iterative multi-plane reflectance measurements. (United States)

    Yariv, Inbar; Haddad, Menashe; Duadi, Hamootal; Motiei, Menachem; Fixler, Dror

    Physiological substances pose a challenge for researchers since their optical properties change constantly according to their physiological state. Examination of those substances noninvasively can be achieved by different optical methods with high sensitivity. Our research suggests the application of a novel noninvasive nanophotonics technique, ie, iterative multi-plane optical property extraction (IMOPE) based on reflectance measurements, for tissue viability examination and gold nanorods (GNRs) and blood flow detection. The IMOPE model combines an experimental setup designed for recording light intensity images with the multi-plane iterative Gerchberg-Saxton algorithm for reconstructing the reemitted light phase and calculating its standard deviation (STD). Changes in tissue composition affect its optical properties which results in changes in the light phase that can be measured by its STD. We have demonstrated this new concept of correlating the light phase STD and the optical properties of a substance, using transmission measurements only. This paper presents, for the first time, reflectance based IMOPE tissue viability examination, producing a decrease in the computed STD for older tissues, as well as investigating their organic material absorption capability. Finally, differentiation of the femoral vein from adjacent tissues using GNRs and the detection of their presence within blood circulation and tissues are also presented with high sensitivity (better than computed tomography) to low quantities of GNRs (<3 mg).

  15. Intensive blood pressure control affects cerebral blood flow in type 2 diabetes mellitus patients. (United States)

    Kim, Yu-Sok; Davis, Shyrin C A T; Truijen, Jasper; Stok, Wim J; Secher, Niels H; van Lieshout, Johannes J


    Type 2 diabetes mellitus is associated with microvascular complications, hypertension, and impaired dynamic cerebral autoregulation. Intensive blood pressure (BP) control in hypertensive type 2 diabetic patients reduces their risk of stroke but may affect cerebral perfusion. Systemic hemodynamic variables and transcranial Doppler-determined cerebral blood flow velocity (CBFV), cerebral CO2 responsiveness, and cognitive function were determined after 3 and 6 months of intensive BP control in 17 type 2 diabetic patients with microvascular complications (T2DM+), in 18 diabetic patients without (T2DM-) microvascular complications, and in 16 nondiabetic hypertensive patients. Cerebrovascular reserve capacity was lower in T2DM+ versus T2DM- and nondiabetic hypertensive patients (4.6±1.1 versus 6.0±1.6 [Phypertensive patients, intensive BP control reduced CBFV in T2DM- (58±9 to 54±12 cm·s(-1)) and T2DM+ (57±13 to 52±11 cm·s(-1)) at 3 months, but CBFV returned to baseline at 6 months only in T2DM-, whereas the reduction in CBFV progressed in T2DM+ (to 48±8 cm·s(-1)). Cognitive function did not change during the 6 months. Static cerebrovascular autoregulation appears to be impaired in type 2 diabetes mellitus, with a transient reduction in CBFV in uncomplicated diabetic patients on tight BP control, but with a progressive reduction in CBFV in diabetic patients with microvascular complications, indicating that maintenance of cerebral perfusion during BP treatment depends on the progression of microvascular disease. We suggest that BP treatment should be individualized, aiming at a balance between BP reduction and maintenance of CBFV.

  16. Retinal blood flow is increased in type 1 diabetes mellitus patients with advanced stages of retinopathy. (United States)

    Nguyen, Hoang-Ton; van Duinkerken, Eelco; Verbraak, Frank D; Polak, Bettine C P; Ringens, Peter J; Diamant, Michaela; Moll, Annette C


    Diabetic retinopathy (DRP) is a common microvascular complication seen in patients with type 1 diabetes mellitus (T1DM). The effects of T1DM and concomitant (proliferative) DRP on retinal blood flow are currently unclear. Therefore, we measured retinal vascular blood flow in T1DM patients with and without DRP and non-diabetic controls. We further assessed the acute effects of panretinal photocoagulation on retinal microvascular bloodflow in eight patients with diabetes. Thirty-three T1DM patients with proliferative DRP, previously treated with panretinal photocoagulation (pDRP), 11 T1DM patients with untreated non-proliferative retinopathy (npDRP) and 32 T1DM patients without DRP (nDRP) were compared with 44 non-diabetic gender-matched controls. Using scanning laser Doppler flowmetry (HRF, Heidelberg) blood flow in the retinal microvasculature was measured temporal and nasal of the optic disc and averaged into one flow value per eye. The right eye was used as a default for further analyses. Eight patients with novel proliferative retinopathy (4 T1DM and 4 with type 2 diabetes) were measured before and several months after photocoagulation. Between-group differences in retinal blood flow were assessed using ANOVA corrected for multiple comparisons (Bonferroni). Retinal blood flow was higher in the treated pDRP compared with the nDRP group and controls (all P Bonferroni linear trend for blood flow with lowest blood flow in the control group and highest in the pDRP group (P-for-trend  0.05). Using regression analysis, no variables were found as predictors of retinal blood flow. In comparison with controls and nDRP patients, retinal blood flow significantly increased in the pDRP group, which previously underwent photocoagulation treatment, but not in the npDRP patients. These changes may be a consequence of a failing vascular autoregulation in advanced diabetic retinopathy.

  17. Effects of non-newtonian properties of blood flow on magnetic nanoparticle targeted drug delivery

    Directory of Open Access Journals (Sweden)

    Mobin Haghdel


    Full Text Available Objective(s: One applications of nanotechnology is in the area of medicine which is called nanomedicine. Primary instruments in nanomedicine can help us to detect diseases and used for drug delivery to inaccessible areas of human tissues. An important issue in simulating the motion of nanoparticles is modeling blood flow as a Newtonian or non-Newtonian fluid. Sometimes blood flow is simulated as a Newtonian fluid but actually blood has nature of non-Newtonian fluid.  Simulation of targeted drug delivery and motion of nanoparticles in the blood flow as Newtonian and non-Newtonian fluid flow is investigated in this paperMaterials and Methods: In this paper, the blood flow is modeled as both Newtonian and non-Newtonian fluid and the effects of each case on the motion of nanoparticles in blood flow and targeted drug delivery is investigated. The flow is modeled with finite volume method. The particle modeled with discrete phase model.Results: Cross, Herschel-Bulkley and Power-law models are used for simulating the non-Newtonian blood flow. Numerical simulations show that trajectory of nanoparticle’s movement and the required time to pass the vessel by blood flow is variable for different models. According to obtained results, non-Newtonian Power-law and Herschel-Bulkley models have closely similar results but they have significant differences compared with Newtonian model. Conclusion: According to the results, it is preferred in the simulation to model blood flow as a non-Newtonian fluid and uses one of Herschel- Bulkley or Power-law models. Otherwise the simulation is far different from real phenomena.

  18. Deep vein thrombosis: A rare complication in oral and maxillofacial surgery: A review of two cases

    Directory of Open Access Journals (Sweden)

    M.R. Ramesh Babu


    Full Text Available Deep vein thrombosis (DVT is caused by obstruction of blood flow of deep veins in upper and lower limb. One of the precipitating factors for DVT is surgery under general anesthesia exceeding 30 min. However, there are very few reports of DVT associated with surgery of oral and maxillofacial region. In this paper we report two cases of DVT involving left ilio-femoropopliteal deep vein in one patient treated for fractured left angle of mandible and left peroneal vein in the other patient treated for oral sub mucous fibrosis. Clinical and color Doppler examination were performed to diagnose the condition and were referred to vascular surgical unit of higher institute for further management. These cases illustrates any surgery of maxillofacial region is not free from risk of DVT, which can cause fatal pulmonary thromboembolism.

  19. Effects of ruminal ammonia and butyrate concentrations on reticuloruminal epithelial blood flow and volatile fatty acid absorption kinetics under washed reticulorumen conditions in lactating dair